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If i=sqrt(-1) , then 4+5(-1/2+isqrt(3)/2...

If `i=sqrt(-1)` , then `4+5(-1/2+isqrt(3)/2)^334+3(-1/2+isqrt(3)/2)^335` is equal to-

A

`1- isqrt(3)`

B

`-1+ i sqrt(3)`

C

`i sqrt(3)`

D

`-i sqrt(3)`

Text Solution

Verified by Experts

The correct Answer is:
C

We know that,
`w =-1/2+sqrt(3)/2i`
`therefore 4+5(-1/2+(isqrt(3))/(2))^334+3(-1/2+(isqrt(3))/2)^365`
`=4+5 omega^(334)+3 omega^(365)`
`=4+5.(omega^3)^111.omega+3.(omega^3)^121.omega^2`
`=4+5 omega + 3 omega^2" "[ because omega^3=1]`
`1+3+2 omega +3 omega+3 omega^2`
`=1+2 omega+3 (1+ omega+omega^2)=1+2 omega + 3xx 0`
`[ because 1+ omega+ omega^2=0]`
`=1+(-1 + sqrt(3i))=sqrt(3i)`
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