a, \(x^2-4+\left(x-2\right)^2\)
= \(x^2-4+x^2-2x.2+2^2\)
= \(x^2-4+x^2-4x+4\)
= \(x^2+x^2-4x\)
= x . ( x + x - 4 )
b, \(x^3-2x^2+x-xy^2\)
= x . ( \(x^2-2x\) + 1 ) - \(xy^2\)
= x . ( x - 1 )\(^2\) - xy\(^2\)
= x . ( x - 1 - xy ). ( x - 1 + xy)
c, \(x^3-4x^2-12x+27\)
=
c/ \(=x^3+27-4x\left(x+3\right)\)
\(=\left(x+3\right)\left(x^2-3x+9\right)-4x\left(x+3\right)\)
\(=\left(x+3\right)\left(x^2-7x+9\right)\)