1. 2x2 – 3x – 9 = 0 2) x2 + 6x – 11 = 0 Warm-up 1/7/15
Find the number of roots or solutions to each quadratic equation below..
2x2 – 3x – 9 = 0
2) x2 + 6x – 11 = 0

2. CCGPS Geometry Day 53 (10-25-13)
UNIT QUESTION: How are real life scenarios represented by quadratic functions?
Today’s Question:
When is it useful to solve quadratics by the quadratic formula?
Standard: MCC9-12..A.REI.4b

3. It’s called finding the discriminant.
notes
There is a way to tell how many roots an equation will have.
It’s called finding the discriminant.
The discriminant is a small part of the quadratic formula.

4. Our text book says solutions instead of roots (same thing).
If the answer is POSITIVE, then you will have 2 roots.
If the answer is ZERO, then you will have 1 root.
If the answer is NEGATIVE, then you will have no roots.
Our text book says solutions instead of roots (same thing).

5. Determine the number of roots. Example: 1
No Roots

6. Determine the number of roots. Example: 2

7. Determine the number of roots. Example: 3

8. Find the number of x-intercepts. Example: 4
two x-intercepts

9. Find the number of x-intercepts. Example: 5
zero x-intercepts

10. Practice Problems

11. Solve for x:

12. Quadratic Formula: gives the solution of in terms of the coefficients a, b & c.
The solutions of the quadratic equation are

13. 1st
Ex: 1 Solve x2+ 9x +14 = 0
2nd
a =
b =
c =

14. example #2
1 and 3

15. Try these on your own:
-5/2 & 2
-1 & 4
2.89 & -1.39