Earlier we saw that y(x)=e3x21 is a composite function that can be written as y(x)=u(v(x)), with v(x)=3x21 and u(v)=ev. By the use of the chain rule we can determine the derivative of this function:
v(x)=32x=6xu(v)=evy(x)=u(v(x))v(x)=ev(x)6x=6xe3x21.