1.求下列齐次方程的通解:-|||-(1) '-y-sqrt ({y)^2-(x)^2}=0;-|||-(2) dfrac (dy)(dx)=yln 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)^dfrac (x{y)})dx+2(e)^x(1-dfrac (x)(y))dy=0.