Is there a simpler approach to these system of equations? I recently came across the following syst

Laila Andrews

Laila Andrews

Answered question

2022-05-14

Is there a simpler approach to these system of equations?
I recently came across the following system of equations:
x + y + z = 1 x 2 + y 2 + z 2 = 2 x 3 + y 3 + z 3 = 3
And I have two questions:
One, is there a way to prove or disprove whether there is a solution for this particular set of equations? Furthermore, is there a way to expand the proof for a more generalized set of equations, that is for this set:
x + y + z = 1 x 2 + y 2 + z 2 = 2 . . . x n + y n + z n = n
Two, is there a simpler approach for the prior solution set than substitution?

Answer & Explanation

Chloe Melendez

Chloe Melendez

Beginner2022-05-15Added 12 answers

Hint:
( x + y + z ) 2 = x 2 + y 2 + z 2 + 2 ( x y + y z + z x )
( x + y + z ) 3 = x 3 + y 3 + z 3 + 3 ( x y + y z + z x ) ( x + y + z ) 3 x y z
So, we can find x + y + z , x y + y z + z x , x y z
Now x , y , z are the roots of
t 3 ( x + y + z ) t 2 + ( x y + y z + z x ) t x y z = 0
I think the same pattern can be applied for the higher powers
enclinesbnnbk

enclinesbnnbk

Beginner2022-05-16Added 5 answers

We will make this into a cubic equation in terms of z. We have

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