x*(1 +y^2)dx=-y *(1-x^2)dx
x *dx/(1-x^2)=ydx/(1+y^2)
(-1/2) ∫ 2xdx/(1-x^2)=(1/2) ∫ 2ydx/(1+y^2)
(-1/2) ln|(1-x^2)|+ln C=(1/2) ln|(1+y^2)|
ln|(1-x^2) |^(-1) +2ln C =ln|(1+y^2)|+2ln C
ln|(1-x^2) |^(-1)+ln C^2=ln|(1+y^2)|
⇒ [b]1+y^2=c/(1-x^2)[/b]
2)
dy/(y^2-3y+2)=dx/tgx
∫ dy/(y^2-3y+2)= ∫ dx/tgx
выделяем полный квадрат,
y^2-3y+2=( y-1,5)^2-0,25
∫ dy/(( y-1,5)^2-0,5^2)= ∫ cosxdx/sinx
1/2*(0,5) ln |(y-1,5-0,5)/(y-1,5+0,5)||=-ln|sinx|+lnC
ln (y-1,5-0,5)/(y-1,5+0,5)=lnC/sinx
[b](y-2)/(y-1)=C/sinx[/b]
3)e^(y)dy=e^(x)dx
∫ e^(y)dy= ∫ e^(x)dx
[b]e^(y)=e^(x) + C [/b]