Because it’s got three inside each of the brackets, so what I’m gonna do is times this massive bracket and then minus b times the bracket and c times the bracket as well, so we do it three times because we have three pre-numbers at the front, times that minus b times that plus c times that I just expanded that out the times a is a squared ab, minus ac, be careful with the signs though and then negative ab, negative b squared, positive bc positive okay don’t make sure you don’t put negative because negative negative makes a positive and here you’ve got ac, bc and then negative c squared,
Do we have any more squares? No. So I don’t need to do anything with that ab I think we have an ab there and an ab there any more ab no ac we’ve got ac there and we’ve also got an ac there and we don’t have any more b squared do we have any b squared no that’s the only one and then bc we’ve got a bc there as well and then c squared. That’s just by itself, so let’s gather up our shapes, so a.. b.. look!!! ab minus ab, what is that guys?? 0! isn’t it, they cancel out, and minus ac plus ac they cancel out and then bc plus bc that’s 2bc, so the answer will be we’ll have an a squared minus b squared minus c squared and we also have the 2bc.
I’ll just put that at the end now you don’t have to put it at the end, you can put it at the front wherever you like but I just did that so it looks like a decent answer.
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