X denotes a random variable with pdf$\displaystyle

f(x)=\left\{\begin{array}{cc}\frac{2}{x^2} & 1 < x < 2\\ 0 &elsewhere \end{array}\right.$

let $\displaystyle Y=X^2$, find the cdf of Y and hence the pdf of Y and cov(X,Y).

I know that to find the pdf from the cdf we differentiate, but I'm not sure how to handle to transformation to $\displaystyle Y = X^2$