Difficulty: Easy
Correct Answer: 4.5
Explanation:
Introduction / Context:
The distance between the roots of a quadratic can be computed without solving for each root explicitly by using the identity |α − β| = sqrt((α + β)^2 − 4αβ). This leverages sum and product of roots from coefficients.
Given Data / Assumptions:
Concept / Approach:
For ax^2 + bx + c = 0, α + β = −b/a and αβ = c/a. Then |α − β| = sqrt((α + β)^2 − 4αβ). This avoids computing α and β separately.
Step-by-Step Solution:
Verification / Alternative check:
Solving explicitly via quadratic formula also yields roots whose difference is 4.5; the identity is quicker and exact.
Why Other Options Are Wrong:
They correspond to common arithmetic slips (e.g., missing the division by a or miscomputing the constant term).
Common Pitfalls:
Using sqrt(b^2 − 4ac)/a directly and forgetting to divide by |a|, which leads to the same value but often mishandled.
Final Answer:
4.5
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