(6cos^4x-sin^2x-1)/(2(2cos^2x -1))怎么化简

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(6cos^4x-sin^2x-1)/(2(2cos^2x -1))怎么化简
(6cos^4x-sin^2x-1)/(2(2cos^2x -1))怎么化简

(6cos^4x-sin^2x-1)/(2(2cos^2x -1))怎么化简
(6cos^4x-sin^2x-1)/[2(2cos^2x -1)]
=(6cos^4 x + cos²x -2) /2(2cos^2x -1)]
=[(3cos²x+2)(2cos²x-1)]/2(2cos^2x -1)]
=(3cos²x+2)/2
=(3/2)*cos²x +1