1)dy/y^2=2xdx
-1/y=x^2+c
y=-1/(x^2+c)
2)y(x^2-1)dy=x(1+y^2)dx
ydy/(1+y^2)=xdx/(x^2-1)
d(y^2)/(1+y^2)=d(x^2)/(x^2-1)
ln(1+y^2)=ln|x^2-1|+c1
1+y^2=c|x^2-1|
1)dy/y^2=2xdx
-1/y=x^2+c
y=-1/(x^2+c)
2)y(x^2-1)dy=x(1+y^2)dx
ydy/(1+y^2)=xdx/(x^2-1)
d(y^2)/(1+y^2)=d(x^2)/(x^2-1)
ln(1+y^2)=ln|x^2-1|+c1
1+y^2=c|x^2-1|