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

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

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

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

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

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

giúp mình câu cuối với

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-2y)(x+2y)-2(x-2y)

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

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

x^2-2x+1-4y^2+4y-1

=(x-1)^2-(2y-1)^2

=(x-1-2y+1)(x-1+2y-1)

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

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

=x²-2²-3(x-2)

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

=(x-2)[(x+2)-3]

=(x-2)(x-1)

BVBHVCKBJCV

x²-x-y²-y=(x²-y²)-(x+y)=(x-y)(x+y)-(x+y)=(x+y)(x-y-1)

x²-xy+x-y=x(x-y)+(x-y)=(x+1)(x-y)

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

PHU HUYNH