Difficulty: Easy
Correct Answer: 3 and 5/2
Explanation:
Introduction / Context:
Factoring is often the fastest way to solve a quadratic with integer coefficients if a suitable factor pair exists. Here the numbers factor cleanly, yielding rational roots without the quadratic formula.
Given Data / Assumptions:
Concept / Approach:
We seek integers m, n such that 2x^2 − 11x + 15 = (2x − 5)(x − 3). Then set each factor to zero to get the roots. This is quicker than the quadratic formula and equally valid.
Step-by-Step Solution:
Verification / Alternative check:
Expand (2x − 5)(x − 3) = 2x^2 − 6x − 5x + 15 = 2x^2 − 11x + 15, confirming correctness.
Why Other Options Are Wrong:
Common Pitfalls:
Misassigning signs to factor pairs of 15, or mixing the coefficient 2 into the wrong factor, leading to cross-term errors.
Final Answer:
3 and 5/2
Discussion & Comments