Question

If (mx + 7)(5x +n)=px^2+15x+14, what is m(n+p)?

A) -10
B) -520
C) 480
D) 2
E) 520

Answer 1

The answer you are looking for is C

Answer 2

(mx + 7)(5x + n) = 5mx^2 + mnx + 35x + 7n
= 5mx^2 + (35 + mn)x + 7n
= px^2 + 15x + 14
7n = 14
n = 2
35+mn = 15
35+ m(2) = 15
35+ 2m = 15
2m = 15-35
2m = -20
m = -10
p = 5m
= 5(-10)
=-50
m(n + p) = -10(2 -50)
= 480