Example: y=x2 +2x-3

a=1 b= +2 c= -3

Step 1. Find and graph the axis of symmetry x=-(b/2a) x=-(2/2(1)) x=-1

The axis of symmetry is the x-value of the ordered pair of the vertex and is expressed

as the vertical line x=___

(-1,-4)

x=(-1)

Steps to graph a function of the form

y=ax2 +bx+c

Step 2. Find and graph the vertex

The x-coordinate is –(b/2a); x=(-1) The y-coordinate is found by substi- tuting the value for x back into the original quadratic and solving for y.

y=(-1)2 +2(-1)-3; y= (-4) vertex = (-1, -4)

(0,-3)(-2,-3)

Step 3. Find and graph the y-intercept and its reflectionSince c is the y-intercept, the points are (0,-3) and the reflection is equidistant from the axis of symmetry (-2,-3)

Step 4. Evaluate the function for another value of x, such as y=12 +2(1)-3=0. Graph (1,0) and its reflection ( -3, 0)

Step 5. Graph all of the points and construct the parabola.

(-1,-4)

(0,-3)(-2,-3)

x=(-1)