⑩天掌 Teaching Plan on Advanced Mathematics o 解2整理得(x2+x3+y)dx+(1+x)d=0, aP 00 1 ∴是全微分方程 A用曲线积分法: u(x,y)=(x2+x3+y)d+的, B凑微分法: 小y+(xd+yd)+xd+xd=0, 中y+d(xy)+d+d=0, d(y+xy++)=0 tianjin polytechnic dmivendityTianjin Polytechnic University Teaching Plan on Advanced Mathematics 解2 整理得 ( ) (1 ) 0, 2 3 x + x + y dx + + x dy = 1 , x Q y P   = =    是全微分方程. A 用曲线积分法: ( , ) ( ) , 0 0 2 3   = + + + x y u x y x x y dx dy B 凑微分法: ( ) 0, 2 3 dy + xdy + ydx + x dx + x dx = 0， 3 4 ( ) 3 4 + + + = x d x dy d xy d ) 0. 3 4 ( 3 4 + + + = x x d y xy