\(a.\) \(3x^2y+6xy\) \(=3xy\left(x+2\right).\)
\(b.x^2\left(x-y\right)+2\left(y-x\right)=\left(x^2-2\right)\left(x-y\right).\)
\(=\left(x-\sqrt{2}\right)\left(x+\sqrt{2}\right)\left(x-y\right).\)
\(c.x^2-y^2+6x+9=\left(x+3\right)^2-y^2.\)
\(=\left(x+3-y\right)\left(x+3+y\right).\)
\(d.x^3+3x^2-4x-12=x^2\left(x+3\right)-4\left(x+3\right).\)
\(=\left(x^2-4\right)\left(x+3\right)=\left(x-2\right)\left(x+2\right)\left(x+3\right).\)
a, 3x^2y+6xy
=3xy(x+2)
b,x^2(x-y)+2(y-x)
=x^2(x-y)-2(x-y)
= (x-y)(x^2-2)
= (x-y)(x-\(\sqrt{2}\))(x+\(\sqrt{2}\))[níu mún chi tiết hơn nx)
c,x^2-y^2+6x+9
=(x-y)(x+y)3(x+3)
=3(x-y)(x+y)(x+3) thuận mắt hơn thì viết như vầy:>
d, x^3+3x^2-4x-12
=x^2(x+3)-4(x+3)
=(x+3)(x^2-4)
=(x+3)(x-2)(x+2)
