#Viet formulas

75 messages · Page 1 of 1 (latest)

fleet tree
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For what values of parameter a is x²-15/4x+a³=0
X²-15/4x+a³=(15/4)²

fleet relicBOT
fleet tree
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And it need's to be done through vieta's formulas

brave dagger
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Can u post the original exercise

fervent sparrow
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For the first you just need to ensure a³ doesnt make the denominator zero

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Try working for what values of x make the fraction zero and go on from there

fleet tree
fervent sparrow
fleet tree
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The exercise says

gusty fog
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Strange. My approach would be to calculate the values of a for which discriminant is >=0 in both equations, and find the common interval.

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I have no idea why or how you would apply vietta sums here

fleet tree
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For what values of parametar a x²-15/4x+a³=0 is equal to x²-15/4x+a³=(15/4)²

gusty fog
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Or are they supposed to be satisfied?

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By a common a?

fleet tree
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Satisfied

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By a parametar a

gusty fog
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Right so using the discriminant approach makes the most sense

fleet tree
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But I dont know is discriminant bigger than a smaller or equal to 0

gusty fog
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I have no idea why you would be asked to use vietta sums

gusty fog
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?

fleet tree
gusty fog
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Because if D could be anything

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then a could also be anything

fervent sparrow
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Oh yeah I forgot vieta sums has barely anything to do with this

gusty fog
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Because there would always be some solution

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So try to form inequalities

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And find the common region

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It is a strange question however

fleet tree
gusty fog
fleet tree
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When I tryed viettas formulas I stopped at one thing and I didnt know how to do it later

fervent sparrow
gusty fog
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The two equations have different roots

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What would you try to achieve by setting up these equations?

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One really tough approach could be somehow finding the transformation that relates the two equations

fleet tree
gusty fog
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Then use that to get equations between 4 different roots

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Then solve for a

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But that makes no sense to do as a serious approach

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You are better off using discriminants

fervent sparrow
# fleet tree I dont understsnd question

The question asks: what values of a allow for some x to give the value of the fraction as 0?

What you have to do: ensure denominators dont go to 0 else the math teacher shits his pants

The problem: vietas relations have to do with the sum and product of the solutions of a polynomial, not 'a'

gusty fog
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Also what denominator?

fervent sparrow
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x²-15/4x+a³ no?

fleet tree
gusty fog
fervent sparrow
fervent sparrow
fleet tree
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/ is division yes

gusty fog
gusty fog
fervent sparrow
gusty fog
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Why would the denominator go to zero for any x?

fervent sparrow
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Ohhh

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I thought it was (x²-15)/(4x+a³)

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Sorryyy

fleet tree
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So I will try D=>0 and tell you what I got

gusty fog
fervent sparrow
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Yeah the only logical thing to do would be to try x is real

fleet tree
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Ok I find the a of the first one and the secound one

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Then did union of both

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Is that an amswer

fervent sparrow
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I mean critically speaking if the quedtion wants both conditios to be satisfied (which it shouldve specified by stating "AND") then you would take an intersection of the soln

gusty fog
gusty fog
fleet tree
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Okay thank you

fleet tree
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