đề sai bét            

=(x^2+x)^2+4(x^2+x)-12

=(x^2+x+6)(x^2+x-2)

=(x^2+x+6)(x+2)(x-1)

moi hok lop 6 

=x^4(x-2)+2x^2(x-2)-3(x-2)

=(x-2)(x^4+2x^2-3)

a: \(x^4-6x^2+8\)

\(=x^4-4x^2-2x^2+8\)

\(=\left(x^2-2\right)\left(x^2-4\right)=\left(x^2-2\right)\left(x-2\right)\left(x+2\right)\)

b: \(x^4-5x^2-14\)

\(=x^4-7x^2+2x^2-14\)

\(=x^2\left(x^2-7\right)+2\left(x^2-7\right)=\left(x^2-7\right)\left(x^2+2\right)\)

c: \(4x^4-7x^2+3\)

\(=4x^4-4x^2-3x^2+3\)

\(=\left(x^2-1\right)\left(4x^2-3\right)=\left(x-1\right)\left(x+1\right)\left(4x^2-3\right)\)

d: \(6x^4+7x^2+2\)

\(=6x^4+3x^2+4x^2+2\)

\(=\left(2x^2+1\right)\left(3x^2+2\right)\)

e: \(x^4-8x^2+15\)

\(=x^4-5x^2-3x^2+15\)

\(=x^2\left(x^2-5\right)-3\left(x^2-5\right)=\left(x^2-5\right)\cdot\left(x^2-3\right)\)

=4(x-y) +(x-y)^2 =(x-y)(x-y+4)

TL:

\(4x-4y+x^2-2xy+y^2\)

\(=4\left(x-y\right)+\left(x-y\right)^2\) 

\(=\left(4+x-y\right)\left(x-y\right)\)

|x|^2 - 2|x|+1 -2 =(|x|-1)^2 - (( căn 2))^2 HĐT a^2 -b^2 sẽ ra 

\(5-7x^2=\left(\sqrt{5}\right)^2-\left(x\sqrt{7}\right)^2\)

\(=\left(\sqrt{5}-x\sqrt{7}\right)\left(\sqrt{5}+x\sqrt{7}\right)\)

\(3+4x=\left(\sqrt{3}\right)^2-\left(2\sqrt{x}\right)^2\) ( do x<0 )

\(=\left(\sqrt{3}-2\sqrt{x}\right)\left(3+2\sqrt{x}\right)\)