Solving Quadratic Equations
Overview
The quadratic equation is one of the most important in all of mathematics, and there is more than one way to crack it. Factorisation is fast when it works, the formula always works, and completing the square reveals the structure that makes the formula possible. A skilled student knows all three and chooses the right tool for each equation.
In this lesson you will solve quadratics by factorising, by the quadratic formula \(x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\), and by completing the square. You will see worked examples of each and learn which method to reach for first.
Objectives
- Solve quadratic equations for real roots by factorisation, by the quadratic formula and by completing the square.
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Solving Quadratic Equations. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Solve x^2 - 5x + 6 = 0. A. x = 1 or x = 6 B. x = 2 or x = 3 C. x = -2 or x = -3 D. x = 5 or x = 6 Answer: B
- Which expression is the quadratic formula? A. (-b +/- sqrt(b^2 - 4ac))/2a B. (-b +/- sqrt(b^2 + 4ac))/2a C. (b +/- sqrt(b^2 - 4ac))/a D. (-b +/- sqrt(4ac - b^2))/2a Answer: A
- Completing the square, x^2 + 6x + 5 equals: A. (x + 3)^2 - 4 B. (x + 3)^2 + 4 C. (x + 6)^2 - 5 D. (x + 3)^2 - 9 Answer: A
- Solve x^2 + 6x + 5 = 0. A. x = 1 or x = 5 B. x = -1 or x = -5 C. x = -1 or x = 5 D. x = 3 only Answer: B
- For 2x^2 - 4x - 3 = 0, the value of b^2 - 4ac is: A. -8 B. 16 C. 40 D. 4 Answer: C
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