求导y=(1+x^3)/(1-x^3)
2个回答

对,用复合函数求导法.

y = (1+x²)/(1-x³)

= -(x³+1)(x³-1)

= -(x³-1+2)(x³-1)

= -[1 + 2/(x³-1)]

= - 1 - 2/(x³-1)

dy/dx = 0 + [2/(x³-1)^2]3x²

= 0 + 6x²/(x³-1)²

或写成:

dy/dx = 6x²/(1-x³)²

一楼的方法是对的,但是y的表达式丢了负号,结果会变成负的,那就错了.

因为求导本身会多出来一个负号,负负得正.结果是正的.