reset
set border
set xtics 1
set ytics 2
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 [-5:5]
set yrange [-20:20]
f(x)=-x**2+2*x+8
# g(x)=x**2-x-56
# h(x)=f(x)/g(x)
plot f(x) ls 1