# Creating and solving a polynomial equal to zero.

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Santos García Rosado le 13 Avr 2021
Hello Mathwork's community,
I'm trying to define as many polynomial functions as columns I have inside an inital matrix A, such as:
A = [-5000 1200 750 2000 1200; -200 150 60 40 50];
Since I have two columns, there'll be two functions that should look like:
Once the polynomial functions have been defiined, I'd like to solve x when the function equals to zero, so that the output for this two cases are:
OutPuts = [0.011369, 0.056055]
I hope I've explained my-self well enough, and that someone could please give me a hand.
Santos
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### Réponse acceptée

Alan Stevens le 13 Avr 2021
Something like this
A = [-5000 1200 750 2000 1200; -200 150 60 40 50];
A = fliplr(A); % Do this in order to use the roots function
R1 = roots(A(1,:)); % roots of first row: 4 values from quartic polynomial
R2 = roots(A(2,:)); % roots of second row: ditto
% R = 1./(1 + x) so x = 1/R - 1
x1 = 1./R1 - 1;
x2 = 1./R2 - 1;
x1(abs(imag(x1))>10^-8)=[]; % delete complex values
x2(abs(imag(x2))>10^-8)=[]; % delete complex values
disp(x1)
disp(x2)
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Santos García Rosado le 13 Avr 2021
Thank you Alan! Simple and elegant!

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