# If f(x)=4x^-5 and g(x)=x^3/4, then what is g(f(x))?

I found: $g \left[f \left(x\right)\right] = \frac{16}{x} ^ 15$
I would use $f \left(x\right)$ inside $g \left(x\right)$ instead of $x$ as:
$g \left[f \left(x\right)\right] = {\left[\textcolor{red}{4 {x}^{-} 5}\right]}^{3} / 4 = \frac{{4}^{3}}{4} \cdot {x}^{-} 15 = {4}^{2} / {x}^{15} = \frac{16}{x} ^ 15$