Question

Factor the trinomial below.

x^2-15x+56

A. (x+4)(x+14)
B. (x+7)(x-8)
C. (x-7)(x-8)
D. (x-4)(x-14)

Answer 1

Answer: Choice C. (x-7)(x-8)

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Find two numbers that...
* Multiply to 56 (last term)
* Add to -15 (middle coefficient)

Those two numbers are -7 and -8. So that's why x^2-15x+56 factors to (x-7)(x-8)