化简:sin^4 x-sin^2 x+cos^2 x

题目

化简:sin^4 x-sin^2 x+cos^2 x

答案

sin^4 x-sin^2 x+cos^2 x=sin^2x(sin^2x-1)+cos^2x=-sin^2xcos^2x+cos^2x=cos^2x(-sin^2x+1)=cos^4x