Asked by  | 17th Jan, 2014, 04:48: PM

Expert Answer:

an = (7 - 4i) + (n - 1)(-1 + 2i) = (7 - n + 1) + I(-4 + 2n - 2) = (8 - n) + (2n - 6)i

(i) For purely real,

2n - 6 = 0

n = 3, i.e., the 3rd term.

(ii) For purely imaginary,

8 - n = 0

n = 8, i.e., the 8th term.

Answered by  | 17th Jan, 2014, 05:07: PM

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