What is the right answer ?

Mar 3, 2018

$4 {x}^{2} - 7 x + 16$

Explanation:

$\textcolor{red}{{\left(x + 4\right)}^{2}} \textcolor{b l u e}{+ 3 x \left(x - 5\right)} = \textcolor{red}{{x}^{2} + 8 x + 16} \textcolor{b l u e}{+ 3 {x}^{2} - 15 x}$
$\textcolor{g r e e n}{{x}^{2}} + \textcolor{p u r p \le}{8 x} + 16 + \textcolor{g r e e n}{3 {x}^{2}} \textcolor{p u r p \le}{- 15 x} = \textcolor{g r e e n}{4 {x}^{2}} \textcolor{p u r p \le}{- 7 x} + 16$
$= E$