I got it! This is what I was going for:
Clear[x, roots, x, n, d];
f[x_] = x^8 - 3 x^5 + x - 1;
n = 5;
der = D[f[x], {x, #}] & /@ Range[n];
roots = Table[NSolve[der[[#]] == 0, x, Reals] & /@ Range[n]];
Grid[{der, roots} // Transpose]
output:
{
{1 - 15 x^4 + 8 x^7, {{x -> -0.5}, {x -> 0.518012}, {x -> 1.22064}}},
{-60 x^3 + 56 x^6, {{x -> 0}, {x -> 0}, {x -> 0}, {x -> 1.02326}}},
{-180 x^2 + 336 x^5, {{x -> 0}, {x -> 0}, {x -> 0.812165}}},
{-360 x + 1680 x^4, {{x -> 0}, {x -> 0.598408}}},
{-360 + 6720 x^3, {{x -> 0.376974}}}
}
Thanks again for your help because I was able to combine what you gave me along with some ideas I was messing around with. Great teamwork and much appreciated!
Brandon