4-1.Complex numbers
easy

${(1 + i)^8} + {(1 - i)^8}$ = . . .

A

$16$

B

$-16$

C

$32$

D

$-32$

Solution

(c) $\,{(1 + i)^2} = \,1 + {i^2} + 2i = 2i$and ${(1 – i)^2} = 1 + {i^2} – 2i = – 2i$
$ \Rightarrow {(1 + i)^8} + {(1 – i)^8} = {(2i)^4} + {( – 2i)^4}$$ = {2^4}({i^4} + {i^4})$
$ = {2^5} = 32.$

Standard 11
Mathematics

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