Q.

If ω1 is a cube root of unity satisfying 1a+w+1b+w+1c+w=2w2 and 1a+w2+1b+w2+1c+w2=2w then the value of 1a+1+1b+1+1c+1is

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a

2

b

-2

c

ω2

d

ω

answer is A.

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Detailed Solution

ω,ω2  are roots of 1a+x+1b+x+1c+x=2x

(b+x)(c+x)+(a+x)(c+x)+(a+x)(b+x)(a+x)(b+x)(c+x)=2xx3x2+2(a+b+c)x+(bc+ca+ab)=2abc+(bc+ca+ab)x+(a+b+c)x2+x3x3(bc+ca+ab)x2abc=0

Sum of the roots =α+ω+ω2=0 α=1

1a+1+1b+1+1c+1=21=2

 

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