Write the function below $in$ the form $y=f(u)$ and $u=g(x).$ Then find $\frac{f}{dx}as$ a function $ofx.$

$y=\sqrt[\phantom{2}]{8x^2-2x+4}$

Write the function $in$ the form $y=f(u)$ and $u=g(x).$ Choose the correct answer below.

$A.y=8u^2-2u+4$ and $u=x$

$B.y=u$ and $u=8x^2-2x+4$

$C.y=\sqrt[\phantom{2}]{u}$ and $u=8x^2-2x+4$

$D.y=8u^2-2u+4$ and $u=\sqrt[\phantom{2}]{x}$

Find $\frac{dy}{dx}as$ a function $ofx.$

$\frac{dy}{dx}=$