2. 1) x +x^3 =x(1 +x²)
2) 5a -10a² =5a(1 -2a)
3) 3a -12 =3(a -4)
4) 3x -3 =3(x -1)
5) x² -2x+1 =(x -1)²=(x -1)(x -1)
6) y² +6y +9=(y +3)²=(y +3)(y+3)
7) 25x² -30xy +9y² =(5x -3y)² =(5x -3y)(5x -3y)
8) a² -1 =(a -1)(a +1)
9) 81x² -16 =(9x -4)(9x +4)
10) 8x² -8y² =8(x² -y²) =8(x -y)(x +y)
11) 3a -3c +xa -xc =3(a -c) +x(a -c) =(a -c)(3 +x)
12) 3a +3a² -b -ab =3a(1 +a) -b(1 +a) =(1 +a)(3a -b)
13) x^3 -8 =(x -2)(x² +2x +4)
14) x^3 +1 =(x +1)(x² -x +1)