1.求下列齐次方程的通解:-|||-(1) '-y-sqrt ({y)^2-(x)^2}=0;-|||-(2) dfrac (dy)(dx)=ycdot dfrac (y)(x);-|||-(3) ((x)^2+(y)^2)dx-xydy=0;-|||-(4) ((x)^3+(y)^3)dx-3x(y)^2dy=0;-|||-(5) (2xsin dfrac (y)(x)+3ycos dfrac (y)(x))dx-3xcos dfrac (y)(x)dy=0;-|||-(6) (1+2(e)^(y^y))dx+2(e)^y'(1-dfrac (x)(y))dly=0.