# Simple Fourier transform problem

1. Mar 2, 2015

### asdf12312

1. The problem statement, all variables and given/known data
Given x[n] with transform X(ejw), find the fourier transform in terms of X(ejw).

x1[n]=[0.9ncos(0.6*pi*n)] * x[n-2]

2. Relevant equations
time shift: x[n-k] -> e-jwkX(ejw)
convolution: x[n] * h[n] -> X(w)H(w)
freq. shift: x[n]ejwcn -> X(ew-wc)

3. The attempt at a solution
I think that this problem has no solution because 0.9n has no Fourier transform (not summable). 0.9nu[n] on the other hand does but not the same case here. am i doing this right?

Last edited: Mar 2, 2015
2. Mar 2, 2015

### Svein

I am at a loss to understand the problem. It seems to me as if the problem is to calculate the Fourier transform of a constant - or a sequence of constants. Is that correct?

3. Mar 2, 2015

### asdf12312

yeah, I guess i didn't word it correctly. what it reads exactly is 'given a sequence x[n] with Fourier transform Xejw, determine the Fourier transform of the sequences in terms of Xejw.

4. Mar 3, 2015

### Svein

Still does not make any sense to me...