3 ms·
Right. And just to be explicit, we're using the fact that (x+1)(x-1) = x² -1. So to add in that step, it would be: 18 x 16 = (17+1)(17-1) = 10(17²-1)
by bumbledraven 11y ago
Right. And just to be explicit, we're using the fact that (x+1)(x-1) = x² -1. So to add in that step, it would be:
18 x 16 = (17+1)(17-1) = 10(17²-1)