2cos^4 x +2sin^2 x-3/2化简

题目

2cos^4 x +2sin^2 x-3/2化简

答案

2cos^4 x +2sin^2 x-3/2 =2cos^4 x +2-2cos^2 x-3/2 =2cos^4 x -2cos^2 x +1/2 =(1/2)*(4cos^4 x -4cos^2 x +1) =(1/2)*(2cosx -1） =(1/2)*cos2x