Answer
Choice B
Work Step by Step
The quadratic function, $f(x)=a(x-h)^2+k$ has vertex at $(h,k)$ and opens up if $a\gt0$ or opens down if $a\lt0$.
The given quadratic function, $
f(x)=5\left( x+\dfrac{1}{2} \right)^2+\dfrac{1}{2}
$ has vertex at $\left(
-\dfrac{1}{2}, \dfrac{1}{2}
\right)$ and opens down since $a\gt0$. Hence, $\text{
Choice B
.}$
