a) \(2x^2+3x-2xy-3y\)

\(\text{=}2x\left(x-y\right)+3\left(x-y\right)\)

\(\text{=}\left(2x+3\right)\left(x-y\right)\)

b) \(x^3-4x^2+4x\)

\(\text{=}x\left(x^2-4x+4\right)\)

\(\text{=}x\left(x-2\right)^2\)

A+B = \(4x^2y^3+6xy-7+\left(-8-3xy-3x^2y^3\right)\)

A+B = \(4x^2y^3+6xy-7-8-3xy-3x^2y^3\text{=}x^2y^3-3xy-15\)

A-B = \(7x^2y^3+9xy+1\)

B-A = \(-7x^2y^3-9xy-1\)