Jawabanmu

2014-09-03T22:04:08+07:00
Hasil adalah
(9a+12-3a^2-4a)(a-5) = (-3a^2+5a+12) (a-5) = (-3a^3-15a^2+5a^2-25+12a-60)
= -3a^3-10a^2+12a-85

2014-09-03T22:05:40+07:00
(3-a)(3a+4) =
9a + 12 -3 a^{2} =
(- 3 a^{2} +9a + 12)(a-5)
- 3 a^{3} + 15 a^{2} + 9a^{2} - 15a + 12a - 60 = - 3 a^{3} + 24 a^{2} - 3a - 60