Quadratic formula

1. Quadratic formula
SOME EXAMPLES….

2. Write this down…
 When you have a quadratic in the form 𝑎𝑥2
+ 𝑏𝑥 + 𝑐 = 0, you can find the
solutions (roots or zeros) by using the quadratic formula.
 𝑥 =
−𝑏± 𝑏2−4𝑎𝑐
2𝑎
 Only replace a, b and c with numbers! No
x’s.

3. Examples…
 The first one is easy…𝑥2
+ 2𝑥 − 8 = 0
 Hint, list out a=___, b=___ and c=___. Remember they are numbers, no
variables allowed.

4. This one has two real
solutions that are
rational.

5. Did you get it? Here is the next one…
 2𝑥2
− 5𝑥 = −1
 Hint: First, get it to say =0, then list a=___, b=___ and c=____

6. This one had 2 real
solutions. They are
irrational because the
number of the radical is
not a perfect square.

7. Last one…
 4𝑥2
+ 3𝑥 + 5 = 7𝑥 + 4
 Hint: get it in standard form (𝑎𝑥2 + 𝑏𝑥 + 𝑐 = 0) 1st.

8. You only have one solution on this one and
It is rational. If the number under the
Radical is zero, you will only have one solution.