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

giúp mình câu cuối với

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

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

2)\(x^2-8x-9y^2+16=\left(x^2-8x+16\right)-9y^2=\left(x^2-8x+4^2\right)-\left(3y\right)^2=\left(x-4\right)^2-\left(3y\right)^2=\left[\left(x-4\right)-3y\right]\left[\left(x-4\right)+3y\right]=\left(x-4-3y\right)\left(x-4+3y\right)\)

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

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

\(=\left(x+2y\right)^2-5^2\)

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

a: \(x^2-4xy+4y^2-2x+4y-35\)

\(=\left(x^2-4xy+4y^2\right)-\left(2x-4y\right)-35\)

\(=\left(x-2y\right)^2-2\left(x-2y\right)-35\)

\(=\left(x-2y\right)^2-7\left(x-2y\right)+5\left(x-2y\right)-35\)

\(=\left(x-2y\right)\left(x-2y-7\right)+5\left(x-2y-7\right)\)

\(=\left(x-2y-7\right)\left(x-2y+5\right)\)

c: \(\left(xy+ab\right)^2+\left(ay-bx\right)^2\)

\(=x^2y^2+a^2b^2+2xyab+a^2y^2-2aybx+b^2x^2\)

\(=x^2y^2+a^2y^2+a^2b^2+b^2x^2\)

\(=y^2\left(x^2+a^2\right)+b^2\left(a^2+x^2\right)\)

\(=\left(x^2+a^2\right)\left(y^2+b^2\right)\)

\(x^2-11x+3\\ =\left(x^2-4x+4\right)-7x-1\\ =\left(x-2\right)^2-\left(\sqrt{7x+1}\right)^2\\ =\left(x-2-\sqrt{7x+1}\right)\left(x-2+\sqrt{7x+1}\right)\)

PHU HUYNH

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

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

`x^2 - 3x - 4`

`<=> x(x - 3)-4`