



 
Shell, There is a great deal of pattern recognition in factoring, by that I mean looking at an expression and seeing patterns you have seen before and recognizing how to factor them. This is true of the "difference of squares" you sent us, x^{2}  y^{2}. Once you think you know the factors you can check by multiplication. Here are three possibilities for factorizations of x^{2}  y^{2}.
Expand each of them and see which simplifies to x^{2}  y^{2}. Penny  


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