reset set border set xtics 1 set ytics 1 set xzeroaxis lt 9 lw 5 set yzeroaxis lt 9 lw 5 set style line 1 lt 1 lw 6 set style line 2 lt 3 lw 3 set style line 3 lt 10 lw 3 set style line 4 lt 12 lw 3 set style line 5 lt 9 lw 1 set grid ls 5 show grid set xrange [-10:10] set yrange [-5:40] # set samples 1000 set key on f(x)=-x**2-7*x+18 #g (x)=0.5*x #h (x)=-2*x+5 # i(x)=4*x**2+40*x+84 plot f(x) ls 1 # plot f(x) ls 1,g(x) ls 2, h(x) ls 3, i(x) ls 4 # plot f(x) ls 1,g(x) ls 2, h(x) ls 3