(m + 3)^2 -16
=(m + 3)^2 - 4^2
=((m+3) + 4)*((m+3) - 4)
=(m+7)(m-1)
Here are the formulas i used:
so first i made 16 to 4^2, then i use (a^2 -b^2)= (a+b)(a-b) . In this case a would be (m+3) and b is 4.
