WAEC SSCE - General Mathematics - 2004 (Objective)

Question 1 Report

Which of the following quadratic equations has $-\frac{1}{2}$ and $\frac{3}{4}$ as its roots?

8x² + 11x - 3 = 0

8x² -11x – 3 = 0

8x² + 2x -3 = 0

8x² - 2x – 3 = 0 Correct answer

Answer Details

The quadratic equation with roots $-\frac{1}{2}$ and $\frac{3}{4}$ can be written in factored form as: $$a(x+\frac{1}{2})(x-\frac{3}{4}) = 0$$ where a is a constant. Expanding this expression, we get: $$a(x+\frac{1}{2})(x-\frac{3}{4}) = ax^2+\frac{1}{8}a = 0$$ Simplifying the equation, we get: $$8ax^2 + a = 0$$ Now we can compare the coefficients of this equation with those in the given options to find the answer. Comparing the coefficients of the given options with our equation, we can see that only the equation: 8x² - 2x - 3 = 0 has the same coefficients, and therefore, the same roots, as the equation we derived. Therefore, the answer is: 8x² - 2x - 3 = 0.






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