a: \(=2x^2+2xy-xy-y^2\)
\(=2X\left(x+y\right)-y\left(x+y\right)=\left(x+y\right)\left(2x-y\right)\)
c: \(x^4-3x^2+1\)
\(=x^4-2x^2+1-x^2\)
\(=\left(x^2-1\right)^2-x^2\)
\(=\left(x^2-x-1\right)\left(x^2+x-1\right)\)
d: \(=\left(x-2\right)\left(x-3\right)\)
e: \(=x^2+10x+25-y^2-6y-9\)
\(=\left(x+5\right)^2-\left(y+3\right)^2\)
\(=\left(x+5-y-3\right)\left(x+5+y+3\right)\)
\(=\left(x-y+2\right)\left(x+y+8\right)\)