In getting the vertex of the quadratic function in general form , we usually need to convert it to the vertex form . In the latter form, the vertex of the parabola is at . For example, the function in the general form
can be rewritten in the vertex form as
In the vertex form, it is easy to see that the vertex is at .
Aside from this method, we can also use the ordered pair
in place of . » Read more
In the Derivation of the Quadratic Formula, we have learned that the solutions to the quadratic equation , where , is described by the equation
Graphically, getting the solutions of is equivalent to getting the value of when of the function , . This means that the quadratic formula above describes the root of the quadratic function .
From the equation, the indicates that the quadratic polynomial can have at most two roots, depending on the value of the expression under the radical sign. That is, the roots of the quadratic polyonomials are
The number of roots, however, will depend on the expression . Notice that if it is negative, there is no root (real root to be exact), since we cannot extract the square root of a negative number. Therefore, if , then, there is no real root. » Read more