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## Quadratic X-Intercepts - Sample Math Practice Problems

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### Complexity=1

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".

 1.   f(x) = - 3x 2 + 36x - 81 x-intercepts: 2.   f(x) = 2x 2 + 2x + 7 x-intercepts:

### Complexity=1

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".

1f(x) = - 3x 2 + 36x - 81
x-intercepts:
Solution
To find the x-intercepts, set the trinomial equal to 0.
- 3x 2 + 36x - 81 = 0
Factor the trinomial.
- 3(x - 3)(x - 9) = 0
Solve for x.
x - 3 = 0
x - 9 = 0
Therefore, the x-intercepts are 3,9

Alternate Solution
You can also use the quadratic formula to find the x-intercepts.

2f(x) = 2x 2 + 2x + 7
x-intercepts:
Solution
To find the x-intercepts, set the trinomial equal to 0.
2x 2 + 2x + 7 = 0
Use the quadratic formula to find the x-intercepts.
Based on ax2 + bx + c, we have:
a = 2, b = 2, c = 7