How to plot the interval of polynomials roots in scilab

We were given lab work with either MatLab or Scilab and pretty much no guidance on how these programs work. And i'am stuck on this exercise: Find polynomial y(x) roots, find the interval to which the roots belong and plot the graph. The equation would be: y(x)=x^5-2. I found the roots myself ( at least I think these are roots ):

 x  = 


   x


p=x^5-2
 p  = 

       5
  -2 +x 

r=real(r)
 r  = 

  -0.9293165
  -0.9293165
   0.3549673
   0.3549673
   1.1486984

So how do I plot graph with this and write the interval?

Solution

Do you mean real roots ? There is only one real root here. You can obtain these roots and plot the graph of the polynomial (and denote the root location) on [0,2] with the following statements:

x = poly(0, "x")
r = roots(x^5-2)
X = linspace(0,2,100)
plot(X, X.^5-2, X, 0*X, r(5), 0, 'x')

 r  = 

  -0.9293165 + 0.675188i
  -0.9293165 - 0.675188i
   0.3549673 + 1.0924771i
   0.3549673 - 1.0924771i
   1.1486984