Math Practice Online > free > lessons > Florida > 9th grade > Quadratic X-Intercepts

Here are some tips for Quadratic X-Intercepts, which aligns with Florida state standards:

For this topic, you will need to know how to factor quadratic equations.
To review, the following topics will help:

An x-intercept is the x-coordinate of the point where a graph intersects the x-axis (also the y = 0 line). Graphs of quadratic equations can have two, one, or no x-intercepts.

To find the x-intercepts of a quadratic equation f(x) = ax2 + bx + c,

1.   Set the equation to zero.
0 = ax2 + bx + c
2.   Use factoring or the quadratic formula to solve for x.

Example 1: Factoring

Find the x-intercepts of each function. Separate multiple answers by commas. Example: x=-3/2,2
If there is no x-intercept, write "none".

f(x) = x2 + 7x + 12     x-intercepts:

Set the equation equal to zero and factor.
 x2 + 7x + 12 = 0 (x + 3)(x + 4) = 0

Solve for x.
 x + 3 = 0 x + 4 = 0 x = -3 x = -4
Therefore, the x-intercepts are -3 and -4.
x-intercepts:

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