例2设y=(於中的 江画工太猩院 dx d(x)d(x) 解 dy dsin(x) cosx'd(x) cosr.2x d 2 2x x d dy dsin(x cosx d() coSX sIn(x cosr alr d(x3)d(x3)l(x3) cosx. 2xdx 2 —cos式 3x23x江西理工大学理学院 例2 ( ) , ( ) sin( ), , 2 3 2 d x dy d x dy dx dy 设y = x 求 解 dx x d x dx d x dx dy [sin( )] cos ( ) 2 2 2 = = 2 2 2 2 2 2 2 cos ( ) cos ( ) ( ) [sin( )] ( ) x d x x d x d x d x d x dy = = = ( ) cos ( ) ( ) [sin( )] ( ) 3 2 2 3 2 3 d x x d x d x d x d x dy = = 2 2 2 cos 3 2 3 cos 2 x x dx x x xdx = ⋅ = 2 2 2 cos cos 2 x x dx x xdx = ⋅ =