WAEC SSCE - Further Mathematics - 2014

If \(\frac{1}{5^{-y}} = 25(5^{4-2y})\), find the value of y.

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To solve the given equation, we can simplify the left-hand side of the equation as follows: \[\frac{1}{5^{-y}} = 5^y\] Similarly, we can simplify the right-hand side of the equation as follows: \[25(5^{4-2y}) = 25 \times 5^4 \times 5^{-2y} = 25 \times 625 \times 5^{-2y} = 15625 \times 5^{-2y}\] Now we can rewrite the given equation as: \[5^y = 15625 \times 5^{-2y}\] Simplifying further, we get: \[5^{3y} = 15625\] Taking the cube root of both sides, we get: \[5^y = 25\] Thus, y = 2. Therefore, the value of y is 2. Answer: (b) 2.

A function is defined by \(h : x \to 2 - \frac{1}{2x - 3}, x \neq \frac{3}{2}\). Find \(h^{-1}(\frac{1}{2})\).

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If \(f(x) = 3x^{3} + 8x^{2} + 6x + k\) and \(f(2) = 1\), find the value of k.

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The function \(f(x)\) is given as \(f(x) = 3x^3 + 8x^2 + 6x + k\), and we are given that \(f(2) = 1\). To find the value of \(k\), we can substitute \(x = 2\) and \(f(2) = 1\) into the function and solve for \(k\). \begin{align*} f(2) &= 3(2)^3 + 8(2)^2 + 6(2) + k \\ 1 &= 24 + 32 + 12 + k \\ 1 &= 68 + k \\ k &= 1 - 68 \\ k &= -67 \end{align*} Therefore, the value of \(k\) is -67.

Find the distance between the points (2, 5) and (5, 9).

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To find the distance between two points in a plane, we can use the distance formula: $$d = \sqrt{(x_2-x_1)^2 + (y_2-y_1)^2}$$ where (x1, y1) and (x2, y2) are the coordinates of the two points. In this case, the given points are (2, 5) and (5, 9), so we can substitute the values into the formula: $$d = \sqrt{(5-2)^2 + (9-5)^2} = \sqrt{3^2 + 4^2} = \sqrt{9+16} = \sqrt{25} = 5$$ Therefore, the distance between the two points is 5 units. So, the answer is option (B).

If the points (-1, t -1), (t, t - 3) and (t - 6, 3) lie on the same straight line, find the values of t.

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If \(8^{x} ÷ (\frac{1}{4})^{y} = 1\) and \(\log_{2}(x - 2y) = 1\), find the value of (x - y).

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Forces 90N and 120N act in the directions 120° and 240° respectively. Find the resultant of these forces.

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Given that \(3x + 4y + 6 = 0\) and \(4x - by + 3 = 0\) are perpendicular, find the value of b.

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Find the derivative of \(\sqrt[3]{(3x^{3} + 1}\) with respect to x.

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To differentiate the function \(\sqrt[3]{(3x^3 + 1)}\), we use the chain rule. Let \(u = 3x^3 + 1\), then we have: \[\frac{d}{dx} \sqrt[3]{(3x^3 + 1)} = \frac{d}{du}u^{1/3}\cdot\frac{d}{dx}(3x^3 + 1)\] Simplifying, we get: \[\frac{d}{dx} \sqrt[3]{(3x^3 + 1)} = \frac{1}{3}(3x^3 + 1)^{-2/3}\cdot(9x^2)\] Simplifying further, we get: \[\frac{d}{dx} \sqrt[3]{(3x^3 + 1)} = \frac{3x^2}{\sqrt[3]{(3x^3 + 1)^2}}\] Therefore, the correct option is (b) \(\frac{3x^2}{\sqrt[3]{(3x^3 + 1)^2}}\).

Simplify: \((1 - \sin \theta)(1 + \sin \theta)\).

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Expanding the given expression using the identity \((a+b)(a-b)=a^2-b^2\), we get: $$(1-\sin\theta)(1+\sin\theta)=1^2-\sin^2\theta=\cos^2\theta$$ Therefore, the simplified expression is \(\cos^{2} \theta\).

If a fair coin is tossed four times, what is the probability of obtaining at least one head?

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When we toss a fair coin, there are two possible outcomes: heads or tails. Since the coin is fair, the probability of getting a head on any given toss is 1/2, and the probability of getting a tail is also 1/2. To find the probability of obtaining at least one head in four tosses, we can use the complement rule: the probability of an event happening is equal to one minus the probability of the event not happening. So, the probability of getting at least one head is equal to 1 minus the probability of getting no heads at all. The probability of getting no heads in one toss is 1/2, and since each toss is independent, the probability of getting no heads in four tosses is (1/2) x (1/2) x (1/2) x (1/2) = 1/16. Therefore, the probability of getting at least one head in four tosses is 1 - 1/16 = 15/16. So, the answer is (D) \(\frac{15}{16}\).

In which group is the upper quartile?

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To find the upper quartile, we need to first calculate the median, which is the value separating the higher half from the lower half of the data. To do that, we can use the formula: Median = ((n + 1) / 2)th term where n is the total number of data points. In this case, n = 6 + 8 + 14 + 10 + 12 = 50. Median = ((50 + 1) / 2)th term Median = 25.5th term Since we have an even number of data points, the median is the average of the two middle terms, which are the 25th and 26th terms when the data is arranged in order. To find these terms, we can use the cumulative frequency distribution: 10-14: 6 15-19: 6 + 8 = 14 20-24: 14 + 14 = 28 25-29: 28 + 10 = 38 30-34: 38 + 12 = 50 The 25th and 26th terms are in the group 20-24, so the median is: Median = (23 + 24) / 2 = 23.5 Next, we need to find the upper quartile, which is the value separating the upper 25% of the data from the lower 75%. We can use the formula: Upper quartile = ((3 * n) + 1) / 4)th term Upper quartile = ((3 * 50) + 1) / 4)th term Upper quartile = 38th term Looking at the cumulative frequency distribution, we see that the 38th term is in the group 25-29. Therefore, the upper quartile is in the group 25-29. The correct option is (C).

Find the equation of a circle with centre (2, -3) and radius 2 units.

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The equation of a circle with center (h,k) and radius r is given by the formula: $$(x-h)^2 + (y-k)^2 = r^2$$ In this case, the center of the circle is (2,-3) and the radius is 2 units. Therefore, we have: $$(x-2)^2 + (y+3)^2 = 2^2$$ Expanding the left-hand side, we get: $$x^2 - 4x + 4 + y^2 + 6y + 9 = 4$$ Simplifying this equation, we get: $$x^2 + y^2 - 4x + 6y + 9 = 0$$ Therefore, the equation of the circle is (A) \(x^{2} + y^{2} - 4x + 6y + 9 = 0\).

Evaluate \(\frac{\tan 120° + \tan 30°}{\tan 120° - \tan 60°}\)

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Given that \(AB = \begin{pmatrix} 4 \\ 3 \end{pmatrix}\) and \(AC = \begin{pmatrix} 2 \\ -3 \end{pmatrix}\), find |BC|.

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To find the length of BC, we need to first find the coordinates of point B and point C. Point B is given as AB = (4, 3). To find point C, we can use the fact that AC + CB = AB. Rearranging, we get CB = AB - AC. Substituting the values we get, CB = \(\begin{pmatrix} 4 \\ 3 \end{pmatrix}\) - \(\begin{pmatrix} 2 \\ -3 \end{pmatrix}\) = \(\begin{pmatrix} 2 \\ 6 \end{pmatrix}\) The length of BC is then given by the formula: |BC| = √((x2 - x1)² + (y2 - y1)²), where (x1, y1) and (x2, y2) are the coordinates of points B and C respectively. Substituting the values we get, |BC| = √((2 - 0)² + (6 - 0)²) = √(4 + 36) = √40 = 2√10 Therefore, the length of BC is 2√10, which is option C.

Find the variance of 1, 2, 0, -3, 5, -2, 4.

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To find the variance of a set of data, we need to follow these steps: 1. Find the mean of the data set. 2. Subtract the mean from each data point, and then square each difference. 3. Find the sum of the squared differences. 4. Divide the sum by the number of data points. To find the variance of 1, 2, 0, -3, 5, -2, 4, we first need to find the mean: mean = (1 + 2 + 0 - 3 + 5 - 2 + 4) / 7 = 7 / 7 = 1 Next, we subtract the mean from each data point and square the differences: (1 - 1)^2 = 0 (2 - 1)^2 = 1 (0 - 1)^2 = 1 (-3 - 1)^2 = 16 (5 - 1)^2 = 16 (-2 - 1)^2 = 9 (4 - 1)^2 = 9 Then we find the sum of the squared differences: 0 + 1 + 1 + 16 + 16 + 9 + 9 = 52 Finally, we divide the sum by the number of data points: 52 / 7 = 7.43 (rounded to two decimal places) Therefore, the variance of the data set is approximately 7.43. So the correct option is (A) \(\frac{52}{7}\).

A ball is thrown vertically upwards with a velocity of 15\(ms^{-1}\). Calculate the maximum height reached. \([g = 10ms^{-2}]\)

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To solve this problem, we can use the formula: \begin{align*} h &= \frac{v_{0}^{2}}{2g} \end{align*} where h is the maximum height reached, \(v_{0}\) is the initial velocity and g is the acceleration due to gravity. Substituting the given values, we get: \begin{align*} h &= \frac{(15\ ms^{-1})^{2}}{2(10\ ms^{-2})}\\ &= \frac{225\ m^{2}s^{-2}}{20\ m s^{-2}}\\ &= 11.25\ m \end{align*} Therefore, the maximum height reached by the ball is 11.25m. Hence, the correct option is (c) 11.25m.

A box contains 5 red and k blue balls. A ball is selected at random from the box. If the probability of selecting a blue ball is \(\frac{2}{3}\), find the value of k.

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Let's first calculate the total number of balls in the box. The box contains 5 red balls and k blue balls, so the total number of balls is 5 + k. The probability of selecting a blue ball can be calculated as follows: P(blue ball) = (number of blue balls) / (total number of balls) We are told that this probability is \(\frac{2}{3}\), so we can set up the following equation: \(\frac{k}{5+k} = \frac{2}{3}\) Cross-multiplying and simplifying, we get: 3k = 10 + 2k k = 10 Therefore, there are 10 blue balls in the box. Answer: 10.

Find \(\lim\limits_{x \to 3} (\frac{x^{3} + x^{2} - 12x}{x^{2} - 9})\)

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To evaluate the limit, we can substitute the value of x into the expression and see what we get. However, in this case, x = 3 would make the denominator 0, and division by 0 is undefined. This suggests that we need to simplify the expression first. We can factor the numerator and denominator, then simplify the expression: \[\lim\limits_{x \to 3} \frac{x^{3} + x^{2} - 12x}{x^{2} - 9} = \lim\limits_{x \to 3} \frac{x(x-3)(x+4)}{(x+3)(x-3)} = \lim\limits_{x \to 3} \frac{x(x+4)}{x+3}\] Now, we can substitute x = 3 into the simplified expression: \[\frac{3(3+4)}{3+3} = \frac{21}{6} = \frac{7}{2}\] Therefore, the answer is \(\frac{7}{2}\).

If \((x + 2)\) and \((3x - 1)\) are factors of \(6x^{3} + x^{2} - 19x + 6\), find the third factor.

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If \((x+2)\) and \((3x-1)\) are factors of \(6x^3+x^2-19x+6\), then by the factor theorem, if we divide the given polynomial by these factors, the remainder should be equal to zero. Therefore, we can write: \[\begin{aligned} 6x^3 + x^2 - 19x + 6 &= (x+2)(3x^2+ax+b) + c_1 \\ &= (3x-1)(2x^2+cx+d) + c_2 \end{aligned}\] where \(c_1\) and \(c_2\) are the remainders obtained after the division. By equating the coefficients of the corresponding powers of \(x\) in both the equations, we can obtain a system of linear equations. Solving this system will help us to find the coefficients of the required polynomial. After solving the system, we get the third factor as \(\boxed{2x-3}\). Therefore, is the correct answer.

What is the class mark of the median class?

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To find the median class, we first need to calculate the cumulative frequency of each class.

A function is defined by \(h : x \to 2 - \frac{1}{2x - 3}, x \neq \frac{3}{2}\). Find \(h^-1\), the inverse of h.

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To find the inverse of a function, you need to switch the roles of x and y, then solve for y. The resulting expression will be the inverse function, denoted as \(h^{-1}\). Starting with the original function: \(h : x \to 2 - \frac{1}{2x - 3}, x \neq \frac{3}{2}\) Switching the roles of x and y: \(x = 2 - \frac{1}{2y - 3}\) Solving for y: \(x - 2 = - \frac{1}{2y - 3}\) \(-2y + 3 = -\frac{1}{x - 2}\) \(-2y = -\frac{1}{x - 2} - 3\) \(y = \frac{1}{2} \cdot \frac{1}{2 - x} + \frac{3}{2}\) \(y = \frac{3x - 7}{2x - 4}, x \neq 2\) Therefore, the inverse function is \(h^{-1} : x \to \frac{3x - 7}{2x - 4}, x \neq 2\). The correct option is (B).

In how many ways can 9 people be seated on a bench if only 3 places are available?

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Since only 3 places are available, the number of ways to choose 3 people out of 9 to fill these seats is given by the combination formula: \[^{9}C_{3} = \frac{9!}{3!(9-3)!} = 84.\] After the selection, the 3 people can be arranged in the available seats in 3! ways, which is 6. Therefore, the total number of ways 9 people can be seated on a bench if only 3 places are available is 84 x 6 = 504. So, the answer is (B) 504.

Using the binomial expansion \((1+x)^{6} = 1 + 6x + 15x^{2} + 20x^{3} + 15x^{4} + 6x^{5} + x^{6}\), find, correct to 3 dp, the value of \((1.98)^{6}\).

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Given that \(x * y = \frac{x + y}{2}, x \circ y = \frac{x^{2}}{y}\) and \((3 * b) \circ 48 = \frac{1}{3}\), find b, where b > 0.

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Find the angle between \((5i + 3j)\) and \((3i - 5j)\).

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The radius of a sphere is increasing at a rate \(3cm s^{-1}\). Find the rate of increase in the surface area, when the radius is 2cm. 

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The surface area, \(A\), of a sphere is given by \(A = 4\pi r^2\), where \(r\) is the radius. We are given that \(\frac{dr}{dt} = 3\text{ cm/s}\) and \(r = 2\text{ cm}\). We want to find \(\frac{dA}{dt}\) at this point. Taking the derivative of the surface area formula with respect to time, we get: \begin{align*} \frac{dA}{dt} &= \frac{d}{dt}(4\pi r^2) \\ &= 8\pi r \frac{dr}{dt} \\ \end{align*} Substituting the given values, we get: \begin{align*} \frac{dA}{dt} &= 8\pi (2\text{ cm})(3\text{ cm/s}) \\ &= 48\pi\text{ cm}^2/\text{s} \\ \end{align*} Therefore, the rate of increase in the surface area when the radius is 2cm is \(48\pi\text{ cm}^2/\text{s}\). So, the answer is (d) \(48\pi cm^{2}s^{-1}\).

Find the coefficient of \(x^3\) in the binomial expansion of \((3x + 4)^4\) in ascending powers of x.

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The deviations from the mean of a set of numbers are \((k+3)^{2}, (k+7), -2, \text{k and (} k+2)^{2}\), where k is a constant. Find the value of k.

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The mean of a set of numbers is the sum of the numbers divided by the total number of numbers. If we have a set of numbers, the deviations from the mean are obtained by subtracting the mean from each number. In this case, we are given the deviations from the mean of a set of numbers, and we need to find the value of k. Let's start by using the fact that the sum of the deviations from the mean is equal to zero. That is: \[(k+3)^2 + (k+7) - 2 + k + (k+2)^2 = 0\] Expanding the squares, we get: \[k^2 + 6k + 9 + k + 7 - 2 + k + k^2 + 4k + 4 = 0\] Simplifying, we obtain: \[2k^2 + 12k + 18 = 0\] Dividing both sides by 2, we get: \[k^2 + 6k + 9 = 0\] This is a quadratic equation that can be factored as: \[(k + 3)^2 = 0\] Therefore, the only solution is: \[k = -3\] So the answer is -3.

Integrate \((x - \frac{1}{x})^{2}\) with respect to x.

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To integrate \((x-\frac{1}{x})^2\) with respect to x, we need to expand the square first: $$(x-\frac{1}{x})^2 = x^2 - 2 + \frac{1}{x^2}$$ Now we can integrate term by term: $$\int (x^2 - 2 + \frac{1}{x^2}) dx = \frac{x^3}{3} - 2x - \frac{1}{x} + c$$ where c is the constant of integration. Therefore, the answer is the option (D).

A particle accelerates at 12\(ms^{-2}\) and travels a distance of 250m in 6 seconds. Find the initial velocity of the particle.

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We can use the equation: distance = initial velocity × time + 0.5 × acceleration × time² We are given the distance as 250m, the time as 6 seconds, and the acceleration as 12\(ms^{-2}\). We need to find the initial velocity. Substituting the values we get, 250 = initial velocity × 6 + 0.5 × 12 × 6² Simplifying, 250 = 6initial velocity + 216 250 - 216 = 6initial velocity 34 = 6initial velocity initial velocity = 34/6 = 5.67 \(ms^{-1}\) (rounded to two decimal places) Therefore, the initial velocity of the particle is 5.67 \(ms^{-1}\), which is option A.

Simplify \(\frac{1 + \sqrt{8}}{3 - \sqrt{2}}\).

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To simplify the given expression, we need to eliminate the square root from the denominator. We can do this by rationalizing the denominator. To do this, we multiply both the numerator and the denominator of the fraction by the conjugate of the denominator. The conjugate of \(3 - \sqrt{2}\) is \(3 + \sqrt{2}\). \begin{align*} \frac{1 + \sqrt{8}}{3 - \sqrt{2}} &= \frac{1 + \sqrt{8}}{3 - \sqrt{2}} \times \frac{3 + \sqrt{2}}{3 + \sqrt{2}}\\ &= \frac{(1 + \sqrt{8})(3 + \sqrt{2})}{(3 - \sqrt{2})(3 + \sqrt{2})}\\ &= \frac{3 + \sqrt{2} + 4\sqrt{2} + 2\sqrt{2}}{7}\\ &= \frac{5\sqrt{2} + 3 + \sqrt{2}}{7}\\ &= \frac{8\sqrt{2} + 3}{7} \end{align*} Therefore, the simplified form of the expression is \(\frac{8\sqrt{2} + 3}{7}\), which corresponds to option (D).

If \(2, (k+1), 8,...\) form an exponential sequence (GP), find the values of k.

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For what values of m is \(9y^{2} + my + 4\) a perfect square?

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If \(Px^{2} + (P+1)x + P = 0\) has equal roots, find the values of P.

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Since the quadratic equation has equal roots, the discriminant is equal to zero. Therefore, we have: $$(P+1)^2 - 4P^2 = 0$$ Simplifying the equation above, we get: $$P^2 + 2P + 1 - 4P^2 = 0$$ $$-3P^2 + 2P + 1 = 0$$ We can now solve for P using the quadratic formula: $$P = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$ where $a=-3$, $b=2$, and $c=1$. Substituting these values, we get: $$P = \frac{-2 \pm \sqrt{2^2 - 4(-3)(1)}}{2(-3)}$$ Simplifying, we have: $$P = \frac{-2 \pm \sqrt{16}}{-6}$$ Therefore, the solutions are: $$P_1 = \frac{-2 + 4}{-6} = \frac{-1}{3}$$ $$P_2 = \frac{-2 - 4}{-6} = 1$$ Hence, the values of P are $\frac{-1}{3}$ and 1. Therefore, the correct option is $\text{: 1 and }\frac{-1}{3}$.

Express (14N, 240°) as a column vector.

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To express (14N, 240°) as a column vector, we need to convert the given magnitude and direction into horizontal and vertical components. We can start by drawing a diagram with a vector starting at the origin and pointing in the direction of 240°. We can then use trigonometry to find the horizontal and vertical components. The horizontal component (x-coordinate) is given by the magnitude (14N) multiplied by the cosine of the angle (240°): $$\text{Horizontal component} = 14\cos(240°) = 14\left(-\frac{1}{2}\right) = -7$$ The vertical component (y-coordinate) is given by the magnitude multiplied by the sine of the angle: $$\text{Vertical component} = 14\sin(240°) = 14\left(-\frac{\sqrt{3}}{2}\right) = -7\sqrt{3}$$ Therefore, the column vector representing (14N, 240°) is: $$\begin{pmatrix} -7 \\ -7\sqrt{3} \end{pmatrix}$$ So the answer is option A: \(\begin{pmatrix} -7 \\ -7\sqrt{3} \end{pmatrix}\).

If \(\frac{x + P}{(x - 1)(x - 3)} = \frac{Q}{x - 1} + \frac{2}{x - 3}\), find the value of (P + Q).

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Find the mean of the distribution.

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If \(T = \begin{pmatrix} -2 & -5 \\ 3 & 8 \end{pmatrix}\), find \(T^{-1}\), the inverse of T.

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The first term of a linear sequence is 9 and the common difference is 7. If the nth term is 380, find the value of n.

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The nth term of a linear sequence can be expressed as follows: nth term = a + (n-1)d where a is the first term, d is the common difference and n is the number of terms. In this question, the first term is 9 and the common difference is 7, so we have: nth term = 9 + (n-1)7 We are told that the nth term is 380, so we can substitute this into the equation and solve for n: 380 = 9 + (n-1)7 380 - 9 = (n-1)7 371 = (n-1)7 n-1 = 371/7 n-1 = 53 n = 54 Therefore, the value of n is 54.

Find the gradient of \(xy^{2} + x^{2} y = 4xy\) at the point (1, 3).

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Find the direction of the resultant of the forces in the diagram.

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A committee of 3 is formed from a panel of 5 men and 3 women. Find the :

(a) number of ways of forming the committee ;

(b) probability that at least one woman is on the committee.

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Solve \((\log_{2} m)^{2} - \log_{2} m^{3} = 10\).

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The position vectors of P, Q and R are \(11i + j, 5i + \frac{13}{3}j\) and \(2i + 6j\) respectively. 

(a) Show that P, Q and R lie on a straight line.

(b) Find the ratio of \(|\overrightarrow{PQ}| : |\overrightarrow{QR}|\)

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If \(\alpha\) and \(\beta\) are the roots of \(3x^{2} + 5x + 1 = 0\), evaluate \(27(\alpha^{3} + \beta^{3})\).

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The probabilities that Kofi, Kwasi and Ama will pass a certain examination are \(\frac{9}{10}, \frac{4}{5}\) and x respectively. If the probability that only one of them will pass the examination is \(\frac{9}{50}\), find the :

(a) value of x ; 

(b) probability that at least one of them will pass the examination.

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The histogram above represents the scores of some candidates in an examination. 

(a) Using the histogram, construct a frequency distribution table indicating clearly the class intervals ;

(b) Draw a cumulative frequency curve of the distribution and use it to estimate the :

(i) median ; (ii) quartile deviation.

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(a) Express \(\frac{5 + \sqrt{2}}{3 - \sqrt{2}} - \frac{5 - \sqrt{2}}{3 + \sqrt{2}}\) in the form \(a + b\sqrt{2}\).

(b) Solve the following equations simultaneously using the determinant method.

\(3x - y - z = -2\)

\(x + 5y + 2z = 5 \)

\(2x + 3y + z = 0\)

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(a) If \(f(x) = \frac{x - 3}{2x - 1} , x \neq \frac{1}{2}\) and \(g(x) = \frac{x - 1}{x + 1}, x \neq -1\), fing \(g \circ f\).

(b)(i) Sketch the curve \(y = 9x - x^{3}\) ; (ii) Calculate the total area bounded by the x- axis and the curve \(y = 9x - x^{3}\).

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(a) A(-1, 2), B(3, 5) and C(4, 8) are the vertices of triangle ABC. Forces whose magnitudes are 5N and \(3\sqrt{10}\)N act along \(\overrightarrow{AB}\) and \(\overrightarrow{CB}\) respectively. Find the direction of the resultant of the forces.

(b) A particle starts from rest and moves in a straight line. It attains a velocity of 20 m/s after covering a distance of 8 metres. Calculate : 

(i) its acceleration ; (ii) the time it will take to cover a distance of 40 metres.

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(a) Differentiate \((x - 3)(x^{2} + 5)\) with respect to x.

(b) If \((x + 1)^{2}\) is a factor of \(f(x) = x^{3} + ax^{2} + bx + 3\), where a and b are constants, find the :

(i) values of a and b ; (ii) zeros of f(x).

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A binary operation \(\ast\) is defined on the set of rational numbers by \(m \ast n = \frac{m^{2} - n^{2}}{2mn}, m \neq 0 ; n \neq 0\).

(a) Find \(-3 \ast 2\).

(b) Show whether or not \(\ast\) is associative.

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(a) Given that \(x = 3i - j, y = 2i + kj\) and the cosine of the angle between x and y is \(\frac{\sqrt{5}}{5}\), find the values of the constant k.

(b) In the quadrilateral ABCD, 

 \(\overrightarrow{AB} = \begin{pmatrix} -5 \\ -1 \end{pmatrix}, \overrightarrow{AC} = \begin{pmatrix} -6 \\ -9 \end{pmatrix}\)

and \(\overrightarrow{BD} = \begin{pmatrix} 4 \\ -7 \end{pmatrix}\). Show whether or not ABCD is a parallelogram.

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The table shows the distribution of the lengths of 20 iron rods measured in metres :

Using an assumed mean of 1.45, calculate the mean of the distribution.

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