Question

1)Rút gọn

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

b)\(\left(a+b+c\right)^2+\left(a-b\right)^2+\left(a-c\right)^2+\left(b-c\right)^2-3\left(a^2+b^2+c^2\right)\)

Answer 1

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

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

\(=a^2\)

Answer 2

b: \(=\left(a+b+c\right)^2+2a^2+2b^2+2c^2-2ab-2ac-2bc-3\left(a^2+b^2+c^2\right)\)

\(=3a^2+3b^2+3c^2-3a^2-3b^2-3c^2\)

=0

a: \(=\left(a+b+c-b-c\right)^2=a^2\)

Answer 3

a,(a+b+c-c)²=a²

b,(a+b+c)²+2a²+2b²+2c²-2ab-2ac-2bc-3(a²+b²+c²)=3a²+3b²+3c²-3a²-3b²-3c²=0