Question

sin^4 x+cos^4 x+2*cos^2 x*sin^2 x​

Answer 1

Ответ:

$sin^4x+cos^4x+2\cdot cos^2x\cdot sin^2x=\\\\\\=\underbrace {(sin^2x)^2+2\cdot sin^2x\cdot cos^2x+(cos^2x)^2}_{a^2+2ab+b^2=(a+b)^2}=(\underbrace {sin^2x+cos^2x}_{1})^2=1^2=1$