试求序列x[k]=3ku[k]+5ku[k]的双边z变换及其收敛域（ ）。
A:
, |z|>5
B:
, |z|<5
C:
, |z|>5
D:
, 3<|z|<5
A:
, |z|>5B:
, |z|<5C:
, |z|>5D:
, 3<|z|<5
举一反三
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