worked example: Differentiate f(x)=(3x2+1)1−3x f′(x)=(6x)(1−3x)+(3x2+1)(21⋅(1−3x)−21⋅(−3)) f′(x)=6x1−3x+(3x2+1)21−3x1⋅−3 f′(x)=6x1−3x−21−3x3(3x2+1)