We can always replace the question mark in for a variable, such as x. So, we have to find x in order to find the missing number.
[tex]v^2 + 10v + 16 = (v + 8)(v + x) \\ \\ \frac{v^2 + 10v+16}{v+8} = v + x \\ \\ \frac{(v+2)(v+8)}{v+8} = v + x \\ \\ v + 2 = v + x \\ \\ 2 = x \\ \\ x = 2 \\ \\ [/tex]
The final result is: x = 2
So, number that makes this equation true is 2.
