Question

Làm cho mình CÂU 3

Answer 1

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

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

\(=3x^2-6xy+3y^2-2x^2-4xy-2y^2-x^2+y^2\)

\(=2y^2-10xy\)

Answer 2

4: Ta có: \(2\left(2x+5\right)^2+3\left(4x+1\right)\left(4x-1\right)\)

\(=8x^2+40x+50+48x^2-3\)

\(=56x^2+40x+47\)