reset
set border
set grid
set xzeroaxis lt 9 lw 2
set yzeroaxis lt 9 lw 2
set style line 1 lt -1 lw 3
set style line 2 lt 5 lw 3
set style line 3 lt 12 lw 3
set xrange [-2.2:2.2]
# set yrange [-0.5:0.15]
# f(x)=-5.3134*x**6+(7*10**-11)*x**5+7.6549*x**4+(10**-10)*x**3-2.9696*x**2-(10**-11)*x+0.118
f(x)=-x**8+8.25*x**6-18*x**4+4*x**2
plot f(x) ls 1