5(1 - xy)(1 + xy)
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Originally Posted by coolman21 5(1 - xy)(1 + xy) You should know the difference of two squares factorisation: , then recognise that is what you need with and to get:
Originally Posted by coolman21 5(1 - xy)(1 + xy) expanding
But if you know the formula mentioned in the other post, you can save yourself some of this trouble.
I am showing all the steps here (just in case) since the problem said "expand and simplify"