Based on the image, all four functions are correctly graphed.
f(x) = x²+1; -2 < x < ∞ is a parabola that opens upwards and has its vertex at (-2, 1). The graph in the image matches this description.
f(x) = 3x^2 + 3; -1 < x ≤ 8 is a parabola that opens upwards and has its vertex at (-1/3, 2/3). The graph in the image matches this description.
f(x) = 2; 0 ≤ x ≤ ∞ is a horizontal line at y = 2. The graph in the image matches this description.
f(x) = -2; -∞ < x < 0 is a horizontal line at y = -2. The graph in the image matches this description.
Therefore, all four graphs are correctly plotted according to their corresponding functions.