Jawabanmu

2014-08-24T19:53:23+07:00
(-a + 3b + 4c) ( -a + 3b +4c ) =  a^{2} - 3ab - 4ac - 3ab -  9b^{2} + 12bc - 4ac + 12bc +  16c^{2}

=  a^{2} - 3ab - 3ab +  9b^{2} + 12bc + 12bc - 4ac - 4ac +   16c^{2}

=  a^{2} - 6ab +  9b^{2} + 24bc - 8ac +  16c^{2}
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