求函数Y=cos(-2X+π/4)的导数
问题描述：
求函数Y=cos(-2X+π/4)的导数
答
y = -sin(-2x+π/4) * (-2x+π/4)' = 2sin(-2x+π/4)=-2sin(2x-π/4)
答
答：
y=cos(-2x+π/4)
y=cos(2x-π/4)
y'(x)=-2sin(2x-π/4)