Joint CDF to Marginal CDF

$F_X(x)={\lim }_{y\to \infty }{F}_{X,Y}(x,y)=F_{X,Y}(x,\infty )$ $F_Y(y)={\lim }_{x\to \infty }{F}_{X,Y}(x,y)=F_{X,Y}(\infty ,y)$