Question

(3x + y)^2 + (x - y)^2

 

Answer 1

\(\left(3x+y\right)^2+\left(x-y\right)^2\)

\(=9x^2+6xy+y^2+x^2-2xy+y^2\)

\(=10x^2+4xy+2y^2\)

\(=2\left(5x^2+2xy+y^2\right)\)

Đề bài là gì bạn ?

Answer 2

\(\left(3x+y\right)^2+\left(x-y\right)^2\\ =\left(3x\right)^2+2.3x.y+y^2+\left(x^2-2xy+y^2\right)\\ =9x^2+6xy+y^2+x^2-2xy+y^2\\ =10x^2+4xy+2y^2\)