x 4 − 7 x 2 + 4 x − 3 = 0
Find the sum of the fifth powers of the roots of the equation above.
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I remembered this answer, it's from Hall & Knight.
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Most of his questions are from either "Hall & Night" or "A.I Prilepko"
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Ahh! revealed your truth.So you see the answers and write here overrated at all the problems
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@Utkarsh Bansal – I have solved these problems earlier they are not level 5 levels , therefore I write overrated there.As you can see I have not written OVERRATED here,I have written overrated in only 2 to 3 problems (not all),So what is the meaning of arguing with me,Also IN the problems where i have written OVERRATED have come down from their particular level.
ALso try to post your "original" problems , that will increase your creativity.
⌣ ¨
Also I am not the only one who says your problems overrated
see this
, this ,
this(calvin sir thinks it is overrated)
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@Parth Lohomi – So please post a solution for this problem @Parth Lohomi and if you think my problems are overrated please try to post solution of this
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@Utkarsh Bansal – Use newtons sum , Also as one studies for RMO these type of questions are practised by him/her > @Utkarsh Bansal I have not solved that problem yet then why are you asking me for a solution?? (you made the question right, then how had you solved it?)
Why do such straight forward questions get to level 5 ?
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It is becoz your problem solving skill is good.Not all of us here has that ability.That's why its level 5
Nice solution sir , Upvoted
Newton's Sums are just so tedious. There must be another way!
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You can multiply the equation by x and sum it in that case you only need P1 P2 and P3. That is not really tedious
Ryan, it can be easily done with a spreadsheet. I can even solve to P 5 0 easily by just hold and drag to copy the formulas. I have edited my solution above.
We can Reduce the calculation a bit by writting x 5 = 7 x 3 − 4 x 2 + 3 x
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The problem can be solved using Newton's Sum method.
Let the roots of the equation be a , b , c and d , then:
⎩ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎧ S 1 = a + b + c + d S 2 = a b + a c + a d + b c + b d + c d S 3 = a b c + a b d + a c d + b c d S 4 = a b c d = 0 = − 7 = − 4 = − 3
And
⎩ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎧ P 1 = a + b + c + d P 2 = a 2 + b 2 + c 2 + d 2 P 3 = a 3 + b 3 + c 3 + d 3 P 4 = a 4 + b 4 + c 4 + d 4 P 4 = a 5 + b 5 + c 5 + d 5 = S 1 = S 1 P 1 − 2 S 2 = S 1 P 2 − S 2 P 1 + 3 S 3 = S 1 P 3 − S 2 P 2 + S 3 P 1 − 4 S 4 = S 1 P 4 − S 2 P 3 + S 3 P 2 − S 4 P 1 = 0 = 1 4 = − 1 2 = 1 1 0 = − 1 4 0
The calculations can be easily done with a spreadsheet as follows: