Question

Упростить -sin²b*cos²b+cos²b-cos⁴b

Answer 1

-sin²b*cos²b+cos²b-cos⁴b=cos²b*(-sin²b)+cos²b*1+cos²b*(-cos²b)=cos²b(-sin²b+1-cos²b)=cos²b*0=0

Answer 2

$-sin^2acdot cos^2a+cos^2a-cos^4a=\\=-sin^2acdot cos^2a+cos^2acdot (underbrace {1-cos^2a}_{sin^2a})=\\=underbrace {-sin^2acdot cos^2a}+underbrace {cos^2acdot sin^2a}=0$