Algebra Question #2

Algebra Level 2

Let r be the sum of the root of x 3 + 1 = 0 x^{3} + 1 = 0 . Find the value of r .

Algebra Question


The answer is 0.

Paul Ryan Longhas by Paul Ryan Longhas , 24, Philippines

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3 solutions

Paul Ryan Longhas
Nov 21, 2014

x^{3} + 1 = 0 ----> (x+1)(x^2 -x + 1)=0, so x= -1 and also the sum of the roots in x^2 -x + 1 is 1. Therefore, -1 + 1 = 0 answer.

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Waaaaaaaaaaaaaaaaaaaaaaaayyyyyyyyyyyyyy overrated

Abdur Rehman Zahid - 6 years, 6 months ago

Also we can use Vieata's formula

Abhisek Mohanty - 5 years, 10 months ago
Ramiel To-ong
May 29, 2015

just use Vietas formula.

2 Helpful 0 Interesting 0 Brilliant 0 Confused

We can do this very quickly with Vieta. he sum of the roots of a cubic equation are -(b/a). As b, which should be of the form bx^2, is not in this equation, b=0. So, 0/1=0. The sum is therefore zero.

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