Nonlinear functions SAT question

The correct answer is $-7$. For a quadratic function defined by an equation of the form  $f(x)=a{(x-h)}^2+k$, where $a$, $h$, and $k$ are constants and $a>0$, the function reaches its minimum when $x=h$. In the given function, $a=1$, $h=-7$, and $k=4$. Therefore, the value of $x$ for which $f(x)$ reaches its minimum is $-7$.