... Cy=2yxM(x)dx + N( y)dy =0M(x) ,N( y)M(x)dx + N( y)dy = Cy2y= x(1 + x2)y2dy −x(1 + x2)dx =0y33−x22−x44= CM1(x )N 1(y)dx + M2(x )N 2(y)dyM2(x )N 1(y)0M1(x)M2(x)dx ... M2(x )N 2(y)dyM2(x )N 1(y)0M1(x)M2(x)dx + N 2(y) N 1(y)dy =0M1(x)M2(x)dx + N 2(y) N 1(y)dy = Cx(1 + y2)dx + y(1 + x2)dy =0(1 + x2)(1 + y2)xdx1+x2+ydy1+y2=0xdx1+x2+ydy1+y2= C12ln(1 ... Rm+1y(x)=(y1(x), ,y n (x))TFR n m mF (x, y, y)=0F (x, y, z)G ⊂ R3y= f(x, y)f D ⊂ R2ey+ y2cos x =1y2− 2xy =lnx∂2u∂x2+∂2u∂y2=0y : I → R n I =(a, b)R mIF...