Question

[Phươngg]

\(\left(a^2+b^2-5\right)^2-4\left(ab+2\right)^2\)

\(=\left(a^2+b^2-5\right)^2-2^2\left(ab+2\right)^2\)

\(=\left(a^2+b^2-5\right)^2-\left(2ab+4\right)^2\)

\(=\left(a^2+b^2-5-2ab-4\right)\left(a^2+b^2-5+2ab+4\right)\)

\(=\left[\left(a^2-2ab+b^2\right)-9\right]\left[\left(a^2+2ab+b^2\right)-1\right]\)

\(=\left[\left(a-b\right)^2-3^2\right]\left[\left(a+b\right)^2-1^2\right]\)

\(=\left(a-b-3\right)\left(a-b+3\right)\left(a-b-1\right)\left(a-b+1\right)\) 

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

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

\(=\left(5-x-4y\right)\left(3+3x+2y\right)\)