These exercises are concerned with functions of two variables.
Let $f(x, y)=x+3 x^{2} y^{2}, x(t)=t^{2},$ and $y(t)=t^{3} .$ Find
$$
\begin{array}{ll}{\text { (a) } f(x(t), y(t))} & {\text { (b) } f(x(0), y(0))} \\ {\text { (c) } f(x(2), y(2))} & {\text { (b) }}\end{array}
$$