Question

Giúp với cần rất gấp

Answer 1

\(a,=x^2-2xy+y^2+x^2+2xy+y^2=2x^2+2y^2=2\left(x^2+y^2\right)\\ ----------\\ b,=\left[\left(x+y\right)-\left(x-y\right)\right]\left[\left(x+y\right)+\left(x-y\right)\right]=\left(x+y-x+y\right)\left(x+y+x-y\right)=2y.2x=4xy\\ ----------\\ c,=\left[\left(2a+b\right)-\left(2a-b\right)\right]\left[\left(2a+b\right)+\left(2a-b\right)\right]=\left(2a+b-2a+b\right)\left(2a+b+2a-b\right)=2b.4a=8ab\\ ----------\\ d,=4x^2-4x+1-2\left(4x^2-12x+9\right)+4=4x^2-4x+5-8x^2+24x-18=-4x^2+20x-13\)