Question

На групування:
1.)7ab+21a-7b-21=
2.)6mn+60-30m-12n=
3.)-abc-3ac-4ab-12a=

Answer 1

1.    7ab + 21a - 7b - 21 = 7a(b+3) - 7(b+3) = (b+3)(7a-7) = -7(b+3)(a-1)
2.    6mn + 60 - 30m - 12n = 6(mn - 5m - 2n + 10) = 6((m-5)(n-2))
3.    -abc - 3ac - 4ab - 12a = -a(bc + 3c + 4b + 12) = -a(b(c+4) + 3(c+4)) = -a(b+3)(c+4)