Question

Rút gọn :(x+y+z)^2 - 2(x+y+z)(x+y)+(x+y)^2

Answer 1

(x + y + z)² - 2(x + y + z)(x + y) + (x + y)²

= (x + y + z + x +y)²

= (2x + 2y + z)²

Chúc bạn học tốt !

Answer 2

\(\left(x+y+z\right)^2-2\left(x+y+z\right)\left(x+y\right)+\left(x+y\right)^2\)

\(=\left[\left(x+y+z\right)-\left(x+y\right)\right]^2\)

\(=\left(x+y+z-x-y\right)^2\)

\(=z^2\)

Áp dụng BĐT: \(\left(a-b\right)^2=a^2-2ab+b^2\)