Using the Quadratic Formula to Find the Rootsy = 3x2 – 6x – 20 The roots are the x values when y = 0
-5
-10
-15
-20
-25
-30
5
-1-2-3-4 1 2 3 4 50X->
|̂Y
Y=3x̂ 2 - 6x- 20
x y-3 25-2 4-1 -110 -201 -232 -203 -114 45 25
From the table you can see that the y values change sign between –2 and –1 and between 3 and 4So the roots lie between –2 and –1 and between 3 and 4
Use your calculator to make a table of values using y = 3x2 – 6x – 20 and the TABLE key
Using the Quadratic Formula to Find the Rootsy = 3x2 – 6x – 20 The roots are the x values when y = 0
a = 3 b = –6 c = –20
-5
-10
-15
-20
-25
-30
5
-1-2-3-4 1 2 3 4 50X->
|̂Y
Y=3x̂ 2 - 6x- 20
The Quadratic formula is used to find the roots
You can check this using x intercept on the CALC menu
Using the Quadratic Formula to Find the Rootsy = 2x2 + 3x – 12 The roots are the x values when y = 0
2x2 + 3x – 12a = 2 b = 3 c = –12
The Quadratic formula is used to find the roots
You can check this using x intercept on the CALC menu
-5
-10
-15
5
-1-2-3-4 1 2 3 4 50X->
|̂Y
Y=2x̂ 2+3x- 12