Difficulty: Medium
Correct Answer: ± 6
Explanation:
Introduction / Context:
The spacing of roots of a monic quadratic can be related directly to its coefficients using Vieta’s relations and the identity |α − β| = sqrt((α + β)^2 − 4αβ). Here, the spacing is fixed at 2; we solve for the parameter p that enforces this.
Given Data / Assumptions:
Concept / Approach:
For monic quadratics, α + β = −p and αβ = 8. Then |α − β| = sqrt((α + β)^2 − 4αβ) = sqrt(p^2 − 32). Set this equal to 2 and solve.
Step-by-Step Solution:
Verification / Alternative check:
With p = 6 or p = −6, compute the discriminant and verify the roots’ difference equals 2; both values work.
Why Other Options Are Wrong:
±2, ±4, ±8 do not satisfy p^2 − 32 = 4; “No real p” contradicts the solution.
Common Pitfalls:
Forgetting the absolute value in the difference or squaring both sides incorrectly.
Final Answer:
p = ±6
Discussion & Comments