Find the value of following expression:
i49 + i68 + i89 + i110
i49 + i68 + i89 + i110 = i(48 + 1) + i68 + i(88 + 1) + i(108 + 2)
= (i4)12 × i + (i4)17 + (i4)11 × i + (i4)27 × i2
= i + 1 + i – 1 = 2i
[since i4 = 1, i2 = – 1]
i49 + i68 + i89 + i110 = 2i