Jawabanmu

2014-09-03T15:27:57+07:00
2p-9q-7r-(-6p+8q-7r)
2p-9q-7r+6p-8q+7r
2p+6p-9q+8q-7r+7r
8p-q
1 1 1
2014-09-03T15:30:00+07:00
-6p+8q-7r dari 2p-9q-7r
=-2p-9q-7r-6p+8q-7r
=2p-6p-9q+8q-7r-7r
=-4p-q