Resolving a non-linear equations

How can I solve the following equation using Matlab:

[Alan Stevens]

You need to provide more detail. What is Dm? What is F(M) and howdoes it connect with the first equation? Are you trying to find M? ...

Answer 1

[Alan Stevens]

Do you mean you want to find the value(s) of M that make the function F(M) = 0.8M(1+M^2)-10 equal to zero? If so then use Matlab's roots function

% F  = 0.8*M^3 + 0.8*M - Dm;
% F = 0.8*M^3 + 0*M^2 + 0.8*M -Dm
Dm = 10;
coeffs = [0.8 0 0.8 -10];
M = roots(coeffs);
disp(M)

[nicole_matlab]

Thank you!