Difficulty: Easy
Correct Answer: −√7 , 13√7 / 7
Explanation:
Introduction / Context:
This quadratic uses an irrational leading coefficient a = √7. We can still apply the quadratic formula to obtain exact roots in terms of √7 and simplify carefully.
Given Data / Assumptions:
Concept / Approach:
Use x = [−b ± √(b^2 − 4ac)] / (2a). Compute the discriminant first; simplify square roots of perfect squares when they appear.
Step-by-Step Solution:
Verification / Alternative check:
Substitute x = −√7: a x^2 = √7*(7) = 7√7; b x = −6*(−√7) = 6√7; c = −13√7. Sum = (7 + 6 − 13)√7 = 0. Likewise, x = 13√7/7 also satisfies the equation.
Why Other Options Are Wrong:
Common Pitfalls:
Dropping √7 during simplification or mishandling rationalization. Keep terms symbolic and only rationalize if needed.
Final Answer:
Discussion & Comments