• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

a question on polynomial... (1 Viewer)

shinigami66

New Member
Joined
Sep 15, 2008
Messages
20
Gender
Male
HSC
2009
is a root of and does not equal to 2,-6

i showed the first question and second question that
i)
ii)

but im up to the third part of the question that asks me to deduce if is a multiple root, then its multiplicity must be 2...

the answer is that if is a multiple root, then must also be a multiple root...
the question i wanna ask is, why is that???
thank you =]

edit: im guessing its something to do with the polynomial's symmetrical property??? mabe not... hah
 

Timothy.Siu

Prophet 9
Joined
Aug 6, 2008
Messages
3,449
Location
Sydney
Gender
Male
HSC
2009
its because roots all at a time =1 right?
but u proved that roots cant be +-1
if alpha is a multiple root, then it has to be 2, because it cant be 3 or 4, or then roots all at a time wont =1
and also if alpha is a multiple root then 1/alpha is too since roots all at a time=1
 

shinigami66

New Member
Joined
Sep 15, 2008
Messages
20
Gender
Male
HSC
2009
i just aint sure why if alpha is a multiple root, then the reciprocal is also a multiple root...
 

Timothy.Siu

Prophet 9
Joined
Aug 6, 2008
Messages
3,449
Location
Sydney
Gender
Male
HSC
2009
i just aint sure why if alpha is a multiple root, then the reciprocal is also a multiple root...
ok, u proved that if A is a root, then 1/A is a root right?

then if A is a multiple root, let the other root be B,
product of roots is A^2 x 1/A x B=1
AB=1
B=1/A
 

SparkyZ

New Member
Joined
Mar 28, 2009
Messages
12
Gender
Male
HSC
2009
You guys all missed the fact that it's actually a Symmetrical Polynomial. Therefore the roots will be reciprocals of each other.
Which only leaves two pairs of reciprocal roots, therefore the maximum multiple root is only two.
 
Last edited:

addikaye03

The A-Team
Joined
Nov 16, 2006
Messages
1,267
Location
Albury-Wodonga, NSW
Gender
Male
HSC
2008
You guys all missed the fact that it's actually a Symmetrical Polynomial. Therefore the roots will be reciprocals of each other.
Which only leaves two pairs of reciprocal roots, therefore the maximum multiple root is only two.
yep, i saw that aswell.
 

shinigami66

New Member
Joined
Sep 15, 2008
Messages
20
Gender
Male
HSC
2009
to GUSSSS - lolx, i used to like animes =p so u might noe where my name came from
to MC - really??? i think it was in one of my skools past paper :S XD
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top