\(=\left(x^2+y^2-5\right)^2-4\left(xy-2\right)^2=\left(x^2+y^2-5+2xy-4\right)\left(x^2+y^2-5-2xy+4\right)\)
\(=\left(\left(x+y\right)^2-9\right)\left(\left(x-y\right)^2-1\right)=\left(x+y-3\right)\left(x+y+3\right)\left(x-y+1\right)\left(x-y-1\right)\)

(x^2+y^2-5)^2 - 4x^2y^2 - 16xy -16
= (x^2 + y^2 - 5)^2 - (4x^2y^2 + 16xy + 16)
= (x^2 + y^2 - 5)^2 - (2xy + 4)^2
= (x^2 + y^2 - 5 - 2xy - 4)(x^2 + y^2 - 5 + 2xy + 4)
= [(x - y)^2 - 9][(x + y)^2 - 1]
=(x-y-3)(x-y+3)(x+y-1)(x+y+1)

4x² - 9y² + 4x - 6y

= (2x - 3y)(2x + 3y) + 2(2x - 3y)

= (2x - 3y)(2x + 3y + 2)

\(4x^2-9y^2+4x-6y\)

\(=\left(4x^2+4x+1\right)-\left(9y^2+6y+1\right)\)

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

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

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

(x²+y²−5)²−4x²y²−16xy−16

= (x²+y²−5)²− (4x²y²+16xy+16)

= (x²+y²−5)²− (2²x²y²+16xy+4²)

=(x²+y²−5)²− ((2xy)²+16xy+4²)

=(x²+y²−5)²− (2xy+4)²

= (x²+y²−5+2xy+4)( x²+y²−5−2xy−4)

= (( x+y)²−1)((x−y)²−9)

= (x+y+1)(x+y−1)(x−y+3)(x−y−3)

\(-4x^2+12xy-9y^2+25=25-\left(2x-3y\right)^2=\left(5-2x+3y\right)\left(5+2x-3y\right)\)

\(-4x^2+12xy-9y^2+25\)

\(=25-\left(4x^2-12xy+9y^2\right)\)

\(=25-\left(2x-3\right)^2\)

\(=\left(5+2x-3\right)\left(5-2x+3\right)\)

\(-4x^2+12xy-9y^2+25\)
\(=\left(-4x^2+12xy-9y^2\right)+25\)
\(=-\left(4x^2-12xy+9y^2\right)+25\)
\(=-\left(2x-3y\right)^2+25\)
Chúc học tốt tick mk nha

2) \(x^4-5x^2+4\)

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

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

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

\(=\left(x-1\right)\left(x+1\right)\left(x-2\right)\left(x+2\right)\)

       x² + 4x + y - 9y²

<=> x(x + 4) + y(1 + 9y)

<=> (x + y)(x + 4 + 1 + 9y)

<=> (x + y)(x + 9y + 5)

bí rồi

a: \(ab+a+b+1\)

\(=a\left(b+1\right)+\left(b+1\right)\)

\(=\left(b+1\right)\left(a+1\right)\)

c: \(4x^2-12xy+3x-9y\)

\(=4x\left(x-3y\right)+3\left(x-3y\right)\)

\(=\left(x-3y\right)\left(4x+3\right)\)