\(a,=\left(x-2y\right)\left(x+2y\right)-2\left(x-2y\right)=\left(x-2y\right)\left(x+2y-2\right)\\ b,=4x^2-y^2+2y-1=4x^2-\left(y-1\right)^2=\left(2x-y+1\right)\left(2x+y-1\right)\\ c,=3x^2+3x-2x-2=3x\left(x+1\right)-2\left(x+1\right)=\left(3x-2\right)\left(x+1\right)\)