A quadratic function is a type of mathematical function that can be expressed in the standard form f(x) = ax^2 + bx + c , where a , b , and c are constants, and a is not equal to zero. The graph of a quadratic function is a parabola, which can open upwards or downwards depending on the sign of a . Quadratic functions have important features, including a vertex, which is the highest or lowest point of the parabola, and the axis of symmetry, a vertical line that divides the parabola into two mirror-image halves. They are commonly used in various fields, such as physics and economics, to model real-world situations.