Question

If n < 0 And 4x²＋mx＋9=(2x＋n)², What Is The Value Of m＋n? A. -15 B. -9 C. -3 D. 12

Answer 1

Answer: A (-15)

Explanation:

Expanding the right side,

4x^2 + mx + 9 = 4x^2 + 4nx +n^2

Comparing both sides, we see that

9 = n^2

m = 4n

Therefore, n = -3 and m = 4(-3) = -12

m + n = -3 + (-12) = -15