Graphing Quadratic Functions in Standard Form

Graphing a quadratic equation in standard form

ax² + bx + c = 0

Steps to graph a quadratic equation

• Be sure it’s in the form ax² + bx + c = 0

• Identify a, b and c

• Use x = -b/2a to find the axis of symmetry

• Plug the x you found into the equation to find y, which is your vertex

• Select 2 more x’s close to one side of the vertex to plug into the equation.

• Reflect those 2 points to the other side of the axis of symmetry.

Poll

Did you read the previous slide? Be honest.

• Yes

• No

Multiple Choice

Is this equation in standard form? If not, what should you do to get it in standard form?

2x² - 20x = 7

• Yes it is in standard form

• No, move the 20x to the other side.

• No, move the 7 to the other side.

• I don't know what standard form is.

Multiple Choice

What is the axis of symmetry for

2x² - 20x + 7 = 0

hint: x = -b/2a

• x = -5

• x = 7/2

• x = 5

• x = -20

Multiple Choice

This is what you should have found so far. Click on the image to enlarge. The next step is to pick 2 x’s close to the axis of symmetry and on the same side of the axis of symmetry. What would you pick? The axis of symmetry is x = 5

• 10 & 20

• 4 & 6

• 3 & 4

• 5 & 6

Poll

If you plug in 3 & 4 for x you’ll get the two points which are now graphed. When a graph has an axis of symmetry, it means the graph is the same on both sides. Do you see that you could reflect the new points across the axis of symmetry to get two more points on the other side? Click on image to make it larger.

• Yes

• No

Open Ended

Here’s what your graph should look like. What questions do you have? Click on the image to view the graph.

What to do next. You decide.

1. Go to www.edpuzzle.com and watch the graphing quadratic equations video, if you haven't already. Sign in using google. Code for 6th period is buznuru. Code for 7th period is ahfedhu.
2. Go to google classroom and work on the graphing parabolas assignment. There are notes and an example at the top of the page.
3. Still have questions. Come back to the google meet and ask me to go over an example.