# How do you evaluate f(-1) given the function f(t)=\frac{1}{2} t^2+4?

$f \left(- 1\right) = \frac{9}{2}$
$\text{to evaluate "f(-1)" substitute "t=-1" into } f \left(t\right)$
$\Rightarrow f \left(\textcolor{red}{- 1}\right) = \frac{1}{2} {\left(\textcolor{red}{- 1}\right)}^{2} + 4 = \frac{1}{2} + 4 = 4 \frac{1}{2} = \frac{9}{2}$