Jawabanmu

2014-09-06T18:52:34+07:00
1. 70 - 30y - 21y - 9y kuadrat
= 70 - 7y - 9y kuadrat

2. 20x kuadrat - 8x - 15x + 6
= 20x kuadrat - 23x + 6
A .(10 - 3y) (7 + 3y) = 10(7+3y) . -3y(7+3y) = (10.7) + (10.3y) - (-3y.7) + (-3y.3y) = 70 + 30y -(-21y) + (-9y^2) = 70 + 51y -9y^2
menurutku jawabannya @natalia no.2 udah bener tp no.1 masih salah.milik @fanyrawan no.1 udh bener tapi no.2 masih salah
2014-09-06T18:53:04+07:00
1. (10 - 3y).(7+3y) = 70 -21y+30y -9y^2 =
   ( -9y^2  + 9y + 70 )

2.  (4x-3).(5x-2) = 20x^2  -8x+8x +6 =
  20x^2 + 6