Question

\ Can anyone explain a and b how they got this answer. what formula they use

P-8.2 For each ofthe following 10-point DF「s, determine a formula the l0-point IDFT Use MATLAB to check your work numerically. 1に0 (a) Xa[k] = 0 k = 1, 2, . . . ,9 (b) Xolk-1 for k = 0, 1,2, ,9 (c)Xc[k] =10 k = 0,1,2, 4, 5, 6, 8, 9 (d) Xalk]cos(2mk/5) for k 0,1,2,...,9 k=3, 7 I (a) Substituting into the inverse DFT definition we get, Xa[n] = 10 k=0 (b) This one is the first entry in Table 8-1, so we can write the answer down by inspection: xb[n-δ[n]. Alternatively, you can plug into the inverse DFT definition and get 9 (2π/10) lon (1 n=0 ] = 10 = δ[n] xhln

Answer 1

6, k 12,9 LD F丁 de bi -'. na(n) = Lo e. 1- lo то (1) peomethce 1-Y ha

JaTT because- 12 r n社1. e' 1-fi

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