[tex]\huge\boxed{\textsf{a.)}\ 10}[/tex]
Substitute [tex]\frac{1}{2}[/tex] for [tex]x[/tex].
[tex]f\left(\frac{1}{2}\right)=5\cdot4^\frac{1}{2}[/tex]
Use [tex]a^\frac{m}{n}=\sqrt[n]{a^m}[/tex].
[tex]\begin{aligned}f\left(\frac{1}{2}\right)&=5\cdot\sqrt[2]{4^1}\\&=5\cdot\sqrt[2]{4}\\&=5\cdot2\\&=\boxed{10}\end{aligned}[/tex]
