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4-1.Complex numbers
medium
$1 + {i^2} + {i^4} + {i^6} + ..... + {i^{2n}}$is
A
Positive
B
Negative
C
Zero
D
Cannot be determined
Solution
(d) $S = 1 + {i^2} + {i^4} + ….. + {i^{2n}} = 1 – 1 + 1 – 1 + …… + {( – 1)^n}$
Obviously it depends on $n$.
Hence cannot be determined unless $n$ is known.
Standard 11
Mathematics