How solve a poly?

Hi, i'm with difficults in solver poly in matlab, for example:

syms x;

fx = x^5 + 2*x^4 + 7*x^3 + 9*x^2 + 8*x - 6

x = 0;

ans = -6

Answer 1

[Star Strider]

If you want the roots of the polynomial, use the vpasolve function:

syms x
fx = x^5 + 2*x^4 + 7*x^3 + 9*x^2 + 8*x - 6
fx_roots = vpasolve(fx == 0)

fx_roots =

                                           0.44238493070265787278357718736358
   - 0.051527066306945417459920042848339 - 2.2932784088204198253304516514344i
     - 1.1696653990443835189318685508335 - 1.0997720388236547546840787557965i
   - 0.051527066306945417459920042848339 + 2.2932784088204198253304516514344i
     - 1.1696653990443835189318685508335 + 1.0997720388236547546840787557965i

[Star Strider]

Rodrigo Franco’s ‘Answer’ moved here:

Nooo.... I don't want the roots of the function, i want just send values in poly

For example:

syms x
fx = x^5 + 2*x^4 + 7*x^3 + 9*x^2 + 8*x - 6

x = 0;

ans = -6

x = 1

ans = .....

[Star Strider]

O.K. If you have R2012a or later, you can create a symbolic funcition:

syms x
f(x) = x^5 + 2*x^4 + 7*x^3 + 9*x^2 + 8*x - 6
f0 = f(0)
f1 = f(1)

f0 =
-6

f1 =
21

Otherwise, use the subs function to get the same result:

fx = x^5 + 2*x^4 + 7*x^3 + 9*x^2 + 8*x - 6
f1 = subs(fx, x, 1)

Answer 2

[Image Analyst]

You can get rid of the "syms" line and just define x before fx:

x = 0;
fx = x^5 + 2*x^4 + 7*x^3 + 9*x^2 + 8*x - 6