Concept:
Just as two points are two pieces of information that uniquely determine a line, a quadratic function is uniquely determined by three pieces of information. The three pieces of information can be three points, or the values of the three coefficients that appear in the standard form of the function, f(x) = a(x - h)2 + k, or the expanded form, f(x) = ax2 + bx + c. Changing the values of any of the coefficients in either form changes the function and its graph.
