reset
set border
set xtics 1
set ytics 1
set grid
set xzeroaxis lt 9 lw 3
set yzeroaxis lt 9 lw 3
set style line 1 lt -1 lw 4
set style line 2 lt 5 lw 3
set style line 3 lt 12 lw 3
set xrange [-10:10]
set yrange [-10:16]
k=-7
f(x)=7*(x-3)**2/25+k
g(x)=x**2+10*x+19
h(x)=-16*x**2/27+12
plot f(x) ls 1,g(x) ls 2, h(x) ls 3