Which two properties of multiplication do we use to simplify complex fractions?

Which two properties of multiplication do we use to simplify complex fractions?

Answer:

what do u mean by properties?
its just (u+v)(u-v)=u^2-v^2 in the denominator (ofc numerator is also multiplied with u-v or u+v whatevs ur question is) and i^2=-1
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