p7 q13

question: a, b, c are real no. prove that if the equation

has two equal roots, then

i know my method is not right:

let

=

so, ......................

RHS = ...............

so finally LHS=RHS

what is the correct method to do it? thanks.

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- May 17th 2008, 07:13 AMafeasfaerw23231233a degree 3 polynomial has two equal roots, prove..
p7 q13

question: a, b, c are real no. prove that if the equation

has two equal roots, then

i know my method is not right:

let

=

so, ......................

RHS = ...............

so finally LHS=RHS

what is the correct method to do it? thanks. - May 17th 2008, 03:30 PMmr fantastic
- May 17th 2008, 09:23 PMNonCommAlg
let be the double root. then i.e. which we'll call it (1), and

which we'll call it (2). if then (1) and (2) gives us b = c = 0, and what you want

to prove obviously holds. so i'll assume that multiply (1) by 3 and (2) by and then add the result

together to get call this (3). now multiply (2) by and (3) by and then add the result

together to get call this one (4). now multiply (2) by and (3) by and then

add the result together to get call this (5). finally multiply (4) by and (5)

by and add the result together to get - May 17th 2008, 10:05 PMmr fantastic