SOLUTION: Graph y=3x^2-5x-9. Also find the vertex

Graph y =  -  - 9. Also find the vertex

a = 3, b = -5, c = -9

Let's find the vertex (h,k) first, where

h =  and k =  +  + 

and then the y-intercept (0,c)

h =  = 

k =  +  +  

k =  +  - 

k =  -  - 

k =  -  - 

k =  

So the vertex is (h,k) = (, )

or for plotting purposes approximately (.8, -11.1)

the y-intercept (0,c) = (0,-9)

So plot the vertex and the y-intercept
      


Draw the left half of the parabola through the
y-intercept and bottoming out at the vertex:



Then draw the right half to match the left half:



Edwin