Difficulty: Medium
Correct Answer: -3, -4 and x^2 + 7x + 12
Explanation:
Introduction / Context:The question leverages Vieta’s formulas: for a monic quadratic x^2 + px + q = 0, the sum of roots is −p and the product is q. Using the information about the two incorrect attempts, we can deduce the true p and q, and hence the correct roots and equation.
Given Data / Assumptions:
Concept / Approach:From the wrong-p attempt: product of roots is still q, thus q = 2*6 = 12. From the wrong-q attempt: sum of roots is still −p, thus −p = 2 + (−9) = −7 ⇒ p = 7. With p and q known, solve the correct quadratic for actual roots.
Step-by-Step Solution:
Wrong-p product ⇒ q = 12.Wrong-q sum ⇒ −p = −7 ⇒ p = 7.Correct equation: x^2 + 7x + 12 = 0.Factor: (x + 3)(x + 4) = 0 ⇒ roots are −3 and −4.Verification / Alternative check:
Check Vieta: sum −3 + (−4) = −7 = −p; product (−3)(−4) = 12 = q. Consistent.Why Other Options Are Wrong:
Common Pitfalls:
Final Answer:
-3, -4 and x^2 + 7x + 12
Discussion & Comments