How to Use the Online Quadratic Solver
This tool simulates the polynomial equation solver function found on the TI-84 Plus graphing calculator. To find the roots (x-intercepts) and vertex of a parabola, follow these steps:
- Enter the coefficient A for the $x^2$ term.
- Enter the coefficient B for the $x$ term.
- Enter the constant C.
- Press the blue ENTER button to calculate.
Understanding the Discriminant
The calculator uses the quadratic formula: $x = \frac{-b \pm \sqrt{b^2 – 4ac}}{2a}$. The value under the square root, $b^2 – 4ac$, is called the discriminant ($\Delta$).
- If $\Delta > 0$: There are two distinct real roots.
- If $\Delta = 0$: There is exactly one real root (the parabola touches the x-axis at one point).
- If $\Delta < 0$: The roots are complex numbers (involving imaginary numbers $i$).
Finding the Vertex
Besides finding the x-intercepts, this tool calculates the vertex of the parabola, which represents the maximum or minimum point of the graph. The x-coordinate is found using $x = \frac{-b}{2a}$, and the y-coordinate is calculated by substituting this x-value back into the equation.