If X∼Exp(1)X \sim \text{Exp}(1)X∼Exp(1), what is the PDF of Y=X2Y = X^2Y=X2?
12ye−y\frac{1}{2\sqrt{y}} e^{-\sqrt{y}}2y1e−y
e−ye^{-\sqrt{y}}e−y
12e−y\frac{1}{2} e^{-y}21e−y
2ye−y22y e^{-y^2}2ye−y2