2005.......complex

find the min value of \left|a+b\omega +c\omega ^{2} \right|
where a,b,c are not equal integers and ω≠1 is cube root of unity..

31 Answers

1
skygirl ·

cauchy scwrtz 'equality' holds wen a=b=c, 1=w=w2...

which is not possible!

1
Kalyan Pilla ·

Thank you Sri

that gets me to understand the soln[1][1]

But still..........What does

"since minimum diffrnce betwn two terms is 1" mean and where does it come from in wats in name's post[7][7]

1
pulsar27 ·

\left| a+b\omega +c\omega^{2}\right| = √(a-b/2-c/2)2 + 3(c-b)2/4=√((a-b)2 + (b-c)2 +( c-a)2)/2

the expression is min. when 2 of the a,b,c are equal

let a=b and b-c=±1 & c-a=±1

so the answer is 1

1
voldy ·

let the iven exprsn be = Z

i.e \left|Z \right| = x

thus x^{2}= Z\bar{Z}

wihch reduces to the above one becos the conjugate ofa+b\omega +c\omega ^{2} is a+b\omega ^{2}+c\omega

so this solves it na ???

1
voldy ·

it depends on this one It think
a^{2}+b^{2}+c^{2}-ab-bc-ca = (a+b\omega +c\omega ^{2})(a+ b\omega ^{2}+c\omega )

that's all wat's in the name has used.

1
ANKIT MAHATO ·

really . .i can't get this answer ! can u please elaborate !

1
Kalyan Pilla ·

nameless are U kidding or is that a serious answer

Can U explain it if it actually is ......[1]

1
°ღ•๓яυΠ·

x=mod of that crap|:P

x^2=square of dat crap :P

so nw
itz

x^2=1/2[(a-b)^2+(b-c)^2+(c-a)^2]
nw a b c r nt equal simulatneously
so d value of dat xperssion is > or = (1+1+0)

so itz > or =1

since minimum diffrnce betwn two terms is 1

so answer is 1
:P

1
skygirl ·

processing........... # # #

1
ANKIT MAHATO ·

anyone has a solution ..

1
ANKIT MAHATO ·

so what to do ..

24
eureka123 ·

i am late.......[3][3]

24
eureka123 ·

cauchy scwarz inequality holds good for all reals......

1
ANKIT MAHATO ·

ok sky go on !!

1
skygirl ·

here though a,b,c are variables but 1,w,w2 are not...

and also given that a≠b≠c ...

we are lucky enuf to get 0 on LHS by properties of complex no..

but that doesnt mean we can use equality here..

1
°ღ•๓яυΠ·

i dnt noe this thm had done it longggggggggggggggggggg back..........

bt iit mein ni ahi so ditch mara :P

1
°ღ•๓яυΠ·

:)

1
ANKIT MAHATO ·

that's what i am asking u yaar !

24
eureka123 ·

ankit......can we use cauchy schwarz for complex nos.????[7][7]

1
ANKIT MAHATO ·

can u point out the error wats i n ur name ?

1
ANKIT MAHATO ·

eureka aren't u intrested !!

1
°ღ•๓яυΠ·

answer is 1 had done this sum few days back :P :P

1
ANKIT MAHATO ·

yaar then how come i got a contradiction !

1
ANKIT MAHATO ·

chauchy - shtwartzur ytu .. some inequality with this kinda name

(a2 + b2 + c2 )(12 + ω2 + (ω2)2) ≥ (a + bω + cω2)2

= 0 ≥ (a + bω + cω2)2

but |a + bω + cω2| not -ve so it is = 0

24
eureka123 ·

ans is 1.............plz give soln...

1
ANKIT MAHATO ·

i got 0 ..

1
°ღ•๓яυΠ·

asnwer is...1...........

memory test :P

1
skygirl ·

ans kya koi no. hai ya a,b,c, mein hai ?

24
eureka123 ·

okzzzz

1
ANKIT MAHATO ·

i am trying dude

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