Octave coding -- solving a quadratic equation and then using the roots

[Ugnius]

Homework Statement

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Relevant Equations

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Hi , I had to solve a quadratic equation , i got two roots as an answer ( ans= x1 / x2) , and now i need to use one of those answers to complete further tasks like finding y from x+y=c so i need to use x1 and x2 from roots , i was wondering if that's possible and how

 

[Mark44]

Homework Statement:: .
Relevant Equations:: .

Hi , I had to solve a quadratic equation , i got two roots as an answer ( ans= x1 / x2) , and now i need to use one of those answers to complete further tasks like finding y from x+y=c so i need to use x1 and x2 from roots , i was wondering if that's possible and how

It seems like you've already done the hard work. The equation $x + y = c$ is equivalent to $y = -x + c$. Can't you just substitute x1 and x2 here and find y?

 

[Ugnius]

It seems like you've already done the hard work. The equation $x + y = c$ is equivalent to $y = -x + c$. Can't you just substitute x1 and x2 here and find y?

yea that what i am not able to do because i don't know what function i need to call to get the root1 and root2 as variables

 

[Ugnius]

i will explain the task - i have to calculate equation system (1.) 6x^2 + 3y^2 = 12 (2.) x+y=2 ; so i can get the x1 and x2 by calculating the first one using substitution , making matrix and calculating roots , but then i need to get y1 and y2 , but i don't know what function i use after the root.

 

[Mark44]

Have you written a function that calculates the roots of a quadratic? Your function, if you have one, should return two values. Show us the Octave code you have.

 

[Ugnius]

Have you written a function that calculates the roots of a quadratic? Your function, if you have one, should return two values. Show us the Octave code you have.

I have solved it 3 AM last night , the point was that roots was a 1x2 matrix , but i could use because it was plugged in octave variable so i created another 1x2 matrix , made it equal to roots(A) matrix , and then i could use B(1) and B(2) to get 1st and 2nd root as variables , thanks for the help tho !