find all zeros

f(x)=21x^3+x

Answer 1

[Honglei Chen]

You can use roots, for example for x^2-1=0

roots([1 0 -1])

http://www.mathworks.com/help/techdoc/ref/roots.html

Answer 2

[Andrei Bobrov]

roots([21 0 1 0])

Answer 3

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/35997-accuracy-of-fzero-in-finallzeros-m

(But Please note the code error I point out in my response.)