Clearly, for C = 0, we obtain y = x2, a parabola with its vertex on the origin The
curve y = x2 + 1 for C = 1 is obtained by shifting the parabola y = x2 one unit along
y-axis in positive direction For C = – 1, y = x2 – 1 is obtained by shifting the parabola
y = x2 one unit along y-axis in the negative direction Thus, for each positive value of C,
each parabola of the family has its vertex on the positive side of the y-axis and for
negative values of C, each has its vertex along the negative side of the y-axis