Verified answer

1) 2a+2b+xa+xb=2(a+b)+x(a+b)=(a+b)(2+x)

2) 3x+ay-ax-3y=3(x-y)+a(y-x)=3(x-y)-a(x-y)=(3-a)(x-y)

3) m²-mn-4m+4n=m(m-n)-4(m-n)=(m-4)(m-n)

4) x³+2x²+x+2=x²(x+2)+x+2=(x²+1)(x+2)