Find the derivative of y with respect to x:
y=3sin^4(2-x)^-1
y=[3sin(2-x)^-1]^4
y'=4[3sin(2-x)^-1]^3 (-3cos(2-x)^-1)(-1) -(2-x)^-2
y'=[12cos(2-x)^-1][3sin^3(2-x)^-1][2-x]^2
but the answer does not have a 3 in front of sin. What happened to the 3?