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Assertion (A): ((-1+sqrt(-3))/(2))^(29)+...

Assertion (A): `((-1+sqrt(-3))/(2))^(29)+((-1-sqrt(-3))/(2))^(29)=-1`
Reason (R ) `omega^(2)=-1`

A

Both A and R are true and R is the correct explanation of A

B

Both A and R are true but R is not the correct explanation of A

C

A is true but R is false.

D

A is false but R is true.

Text Solution

Verified by Experts

The correct Answer is:
C

Consider `[(-1+sqrt(-3))/(2)]^(29)+[(-1-sqrt(-3))/(2)]^(29)`
`[(-1+sqrt(3i))/(2)]+[(-1sqrt(3i))/(2)]^(29)`
`(omega)^(29)+(omega^(2))^(29)=omega^(27).omega^(2)+(omega^(3))^(19).omega`
`=(omega^(3))^(9)omega^(2)+(omega^(3))^(19).omega`
`=1.omega^(2)+1.omega" "(becauseomega^(3)=1)`
`=omega^(2)+omega=-1`
`(R) omega^(2)ne-1`
A is true but R is false.
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NDA PREVIOUS YEARS-COMPLEX NUMBERS-Multiple choice question
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  2. If 2x=3+5i, then what is the value of 2x^(3)+2x^(2)-7x+72?

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  3. Assertion (A): ((-1+sqrt(-3))/(2))^(29)+((-1-sqrt(-3))/(2))^(29)=-1 ...

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  4. If alpha is a complex number such that alpha^(2)+alpha+1=0, then wha...

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  5. What is the modulus of |(1+2i)/(1-(1-i)^(2))|?

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  6. What is the value of (-sqrt(-1))^(4n+3)+(i^(41)+1^(-257))^(9), when n...

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  7. If omega is the cube root of unity, then what is the con jugate of 2om...

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  8. If z is a complex number such that z+z^(-1)=1, then what is the value ...

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  9. What is the value of ((i+sqrt3)/(-i+sqrt3))^(200)+((i-sqrt3)/(i+sqrt3)...

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  10. If omega is complex cube root of unity ans x=omega^(2)-omega-2, then w...

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  11. If x^(2)+y^(2)=1, then what is (1+x+iy)/(1+x-iy) equal to ?

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  12. What is the modulus of |(1+2i)/(1-(1-i)^(2))|?

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  13. What is the least positive integer n for which ((1+i)/(1-i))^(n)=1 ?

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  14. What is the conjugate of ((1+2i)/(2+i))^(2)?

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  15. What is ((sqrt3+i)/(sqrt3-i))^(6) equal to ?

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  16. If omega is a complex cube root of unity, then what is omega^(10)+om...

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  17. What is the value of (-1+isqrt3)^(48)?

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  18. What is the vlaue of 1+i^(2)+i^(4)+i^(60)+....+i^(100), where i=sqrt...

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  19. If z=1+cos(pi/5)+isin(pi/5) then sin(argz) is equal to

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  20. What is modulus of (1)/(1+3i)-(1)/(1-3i) ?

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