a, \(=\left(xy+1+x-y\right)\left(xy+1-x+y\right)\)
b, \(\left(x+y-x+y\right)[\left(x+y\right)^2+\left(x+y\right)\left(x-y\right)+\left(x-y\right)^2]\)
\(=2y[x^2+2xy+y^2+x^2-y^2+x^2-2xy+y^2]\)
\(=2y\left(3x^2+y^2\right)\)
c,\(=3\left(x+1\right)^2\left(x^2-x+1\right)y^2\)
câu a, b áp dụng hằng đẳng thức rồi làm nha
c) 3x4y2 + 3x3y2 + 3xy2 + 3y2
= ( 3x4y2 + 3x3y2 ) + ( 3xy2 + 3y2 )
= 3x3y2 ( x + 1) + 3y2 ( x + 1 )
= ( 3x3y2 + 3y2 ) ( x + 1 )
= 3y2 ( x3 + 1 ) ( x + 1 )
= 3y2 ( x + 1 ) ( x2 - x + 1 ) ( x + 1 )
= 3y2 ( x + 1 )2 ( x2 - x + 1 )
a) (xy +1)2- (x-y)2
=(xy +1-x+y)(xy+1+x-y)
b) (x + y)3 - (x - y)3
= (x+y-x+y)((x+y)2+(x+y)(x-y)+(x - y)2)
= 2y(x2+2xy+y2+x2+xy-xy-y2+x2-2xy+y2)
=2y(3x2+y2)
c) 3x4y2 + 3x3y2 + 3xy2 + 3y2
=3y2(x4+x3+x+1)
= 3y2(x3(x+1)+(x+1)
= 3y2(x+1)(x3+1)
ko bt đúng ko
a) Ta có: \(\left(xy+1\right)^2-\left(x-y\right)^2\)
\(=\left(xy+1-x+y\right)\left(xy+1+x-y\right)\)
b) Ta có: \(\left(x+y\right)^3-\left(x-y\right)^3\)
\(=x^3+3x^2y+3xy^2+y^3-x^3+3x^2y-3xy^2+y^3\)
\(=2y^3+6x^2y\)
c) Ta có: \(3x^4y^2+3x^3y^2+3xy^2+3y^2\)
\(=3y^2\left(x^4+x^3+x+1\right)\)
\(=3y^2\left(x+1\right)\left(x^3+1\right)\)
\(=3y^2\left(x+1\right)^2\cdot\left(x^2-x+1\right)\)
c) 2x2(x +1) + 4x(x +1); d) 2 x(y - 1) - 2