Question

(a+b+c)^2-2(a+b+c)(b+c)+(b+c)^2

Answer 1

\(\left(a+b+c\right)^2-2\left(a+b+c\right)\left(b+c\right)+\left(b+c\right)^2\)

\(=\left[\left(a+b+c\right)-\left(b+c\right)\right]^2\)

\(=a^2\)

Answer 2

`(a+b+c)^2-2(a+b+c)(b+c)+(b+c)^2`

`=(a+b+c-b-c)^2`

`=a^2`

Áp dụng hđt2

Answer 3

đề là j bn