The marginal probability density function of X is Fxx = ∫02f(x,y) dy Fxx = ∫02k ( x+2y ) dy Fxx = k xy+ 2y2 2 02 Fxx = k [ 2x+4 - 0 ] Fxx = k 2x+4 ; 0<x<1. The marginal probability density function of Y is FYy = ∫01f(x,y) dx Fxx = ∫01k ( x+2y ) dx Fxx = k x22+2xy 01 Fxx = k [ ( 122+2y(1) ) - 0 ] Fxx = k 12+2y ; 0<y<2.