f (x) = 3 (1/5)^3-×, nilai f (5) adalah

[tex]$\begin{align}f(x)&=3\left(\frac15\right)^{3-x}\\f(5)&=3\left(\frac15\right)^{3-5}\\&=3\left(\frac15\right)^{-2}\\&=3\times5^2\\&=3\times25\\&=\boxed{75}\end[/tex]