Mathematica数学实验求根

f[x_] := Exp[x] - Cos[x]
Plot[f[x],{x,-20,20},AxesLabel -> {"x","f(x)"},PlotRange -> All]
Plot[f[x],{x,-20,0}]
{FindRoot[f[x] == 0,{x,-20}],FindRoot[f[x] == 0,{x,-17.5}],
FindRoot[f[x] == 0,{x,-15}],FindRoot[f[x] == 0,{x,-10}],
FindRoot[f[x] == 0,{x,-5}],FindRoot[f[x] == 0,{x,0}]}
Reverse[Drop[%,1]]
{{x -> 0.},{x -> -4.72129},{x -> -10.9956},{x -> -14.1372},{x ->
-17.2788}}
以上符合题意不?