Show[Plot[3 x^2 + 2 x - 4, {x, -3, 5}, PlotRange -> {{-4, 6}, {-10, 85}}], AxesLabel -> {"x-axis", "y-axis"}, Epilog -> {PointSize[Medium], Red, Point[{{-3, 3 ((-3)^2) + 2 (-3) - 4}, {5, 3 ((5)^2) + 2 (5) - 4}}]}, ImageSize -> 270]