5

Set 11: Quadratic Equations

Explanation

Answer: C

Which of the following is a factor of x2+3x10x^2 + 3x - 10?

A.

(x5)(x - 5)

B.

(x+2)(x + 2)

C.

(x2)(x - 2)

✓ Correct
D.

(x+10)(x + 10)

Detailed Explanation

Choice C is correct. Choice C is the correct answer. We need to factor x2+3x10x^2 + 3 x - 10. We seek two numbers that multiply to -10 and add to +3. 1. Factors of -10: (-1, 10), (1, -10), (-2, 5), (2, -5). 2. Sums: 1+10=9-1+10=9, 110=91 -10=-9, 2+5=3-2+5=3, 25=32 -5=-3. 3. The correct pair is -2 and 5. So, the expression factors as (x2)(x+5)(x - 2)(x + 5). Therefore, (x2)(x - 2) is one of the factors. Choice A is incorrect because the factor is (x+5)(x+5), not (x5)(x-5). Choice B is incorrect because the factor is (x2)(x-2), not (x+2)(x+2). Choice D is incorrect because 10 is not part of the correct factor pair.

Key Steps:

The correct answer is (x2)(x - 2)

Why others are wrong:
A: Choice A is incorrect and may result from a calculation error.
B: Choice B is incorrect and may result from a calculation error.
D: Choice D is incorrect and may result from a calculation error.

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