A parabola is a special curve shaped like an arc. The standard form of a parabola is y = ax2 + bx + c. The vertex form is y = a(x-h)2 + k, where (h,k) is the vertex. If a > 0, then the parabola opens upwards. If a < 0, then it opens downward.
Good to know! If the absolute value of a < 1, the graph of the parabola widens. If the absolute value of a > 1, the graph becomes narrower.