看作是复合函数 y=u^2 u=sinv v=2x+π/3
分别对其求导,并相乘
所以 y'=2sin(2x+π/3)*cos(2x+π/3)*2
y'=4sin(2x+π/3)cos(2x+π/3)=2sin(4x+2π/3)
对于你问的cos(2x+π/3)后面为什么乘以2,是对V求导得2
y'=2sin(2x+π/3)； u′=cos(2x+π/3)：v′=2这三者相乘得 y'=2sin(2x+π/3)*cos(2x+π/3)*2