# HW7 discussion, ECE301 Spring 2011, Prof. Boutin

I think the table of DT Fourier Transform pairs has a mistake. where it says $ (n-1)a^nu[n] $ it should be $ (n+1)a^nu[n] $ instead according to the book and our notes.

- It's possible. Are you sure that your notes are correct? Can you find a way to double check? If so, then go ahead and change the formula in the table. It's a collective table after all!-pm

Can you provide an example of what we need to do for question 5?

- Look in your course notes. Locate the place where we got the expression for the frequency response from a difference equation. Look at all the steps we carried out in order to get that expression: to answer part a), just carry out these steps in reverse order. -pm

for question 5, I'm having a hard time dealing with the second frequency response. The bottom is not factorable, and I'm not sure how to deal with it. If it factored, I could easily use a formula from the table, but it doesn't factor. Am I missing something?

- The bottom must be factorable, because polynomial equations of degree two are always factorable (if you allow the factors to be complex numbers). You may want to try factoring using the quadratic formula. -pm