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Montes
In problem set 3. Exercise 2A-7. how do you get the final step of the answer from 1/(1-x^2) to approximately 1+x^2... Is it because of "the linear approx" of the linear approx?
Yep, 1/(1-x^20*(1+x^2)/(1+x^2) and drop all powers of x above 2