Math CentralQuandaries & Queries


Question from Nazrul, a teacher:

If x is proportional to y , how can I prove that (x^2-y^2) is proportional to xy.
Please explain the process.


The statement "x is proportional to y" or more completely "x is directly proportional to y" means that x is a constant times y. Thus there is some constant k so that x = k y. Substitute this expressions into x2 - y2 and xy and see if you can show that one is a constant times the other.


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