Question

Ảnh bình luận ạ

Answer 1

  

Answer 2

53:

\(f\left(x\right)=3\left[\left(sin^2x+cos^2x\right)^2-2\cdot sin^2x\cdot cos^2x\right]-2\left[\left(sin^2x+cos^2x\right)^3-3\cdot sin^2x\cdot cos^2x\left(sin^2x+cos^2x\right)\right]\)

\(=3\left[1-2\cdot sin^2x\cdot cos^2x\right]-2\cdot\left[1-3sin^2x\cdot cos^2x\right]\)

\(=3-6\cdot sin^2x\cdot cos^2x-2+6\cdot sin^2x\cdot cos^2x\)

=1
=>A

54:

\(f\left(x\right)=cos^2x\left(cos^2x+sin^2x\right)+sin^2x\)

=cos^2x+sin^2x

=1

=>A

55:

\(A\left(x\right)=tan^2x\cdot sin^2x-tan^2x+sin^2x\)

\(=tan^2x\left(sin^2x-1\right)+sin^2x\)

\(=-tan^2x\cdot cos^2x+sin^2x\)

\(=-sin^2x+sin^2x=0\)