16. Rewrite the middle term as the sum of two terms and then factor by grouping.
x2 – 2x – 63
17. Factor. 9x(x – 7y) – 6(x – 7y)
18. Factor completely. print_coeff(a*c,1)x2 print_coeff(a*d,0)xy print_coeff(b*c,0)x print_coeff(b*d,0)y
19. Rewrite the middle term as the sum of two terms and then factor completely.
15x2 – 21x + 6
20. Rewrite the middle term as the sum of two terms and then factor completely.
x2 + 19x + 90
21. Factor completely. ax – ay + x2 – xy
22. Rewrite the middle term as the sum of two terms and then factor by grouping.
x2 + 4x – 12
24. Rewrite the middle term as the sum of two terms and then factor by grouping.
x2 – 14x + 45
25. Factor by grouping. x3 – 3x2 + 4x – 12