Find the roots of the quadratic equation: x2 + 2x - 15 = 0?
Correct answer: A. -5, 3
- A. -5, 3
- B. 3, 5
- C. -3, 5
- D. -3, -5
Explanation
The equation x^2 + 2x - 15 = 0 factors as (x + 5)(x - 3) = 0. Therefore the roots are x = -5 and x = 3. Students may choose option c by reversing the signs of both roots, misunderstanding the factors of -15.
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About Quadratic Equations
Quadratic equations contain a squared variable and can be solved by factorisation, completing the square, the quadratic formula, or graphical reasoning. Questions cover roots, the discriminant, and the relationship between roots and coefficients, while distinguishing real and repeated roots from complex or non-real roots.
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