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The density of Z = X Y and of W = Y −X2 Since X and Y are independent, we know that f(x,y) = fX(x)fY (y), giving us f(x,y) = ˆ λe−λxλe−λy if x,y ≥ 0 0 otherwise The first thing we do is draw a picture of the support set the first quadrant (a) To find the density, fZ(z), we start, as always, by finding the cdf, FZ(z) = P(ZY(y) = P(Y y) = P(g(X) y) = Z A(y) p X(x)dx where A(y) = fx g(x) yg The density is p Y(y) = F0 Y (y) If gis strictly monotonic, then p Y(y) = p X(h(y)) dh(y) dy where h= g 1 Example 3 Let p X(x) = e x for x>0 Hence F X(x) = 1 e x Let Y = g(X) = logX Then F Y(y) = P(Y y) = P(log(X) y) = P(X e y) = F X(e) = 1 e e y and p Y(y) = eye e y forAlgebra Rational Equations and Functions Inverse Variation Models 1 Answer Jim G #y=(3xz)/(2w)# Explanation #"the initial statement is " yprop(xz)/w# Dpsd Notes Notes Z y w