How do you use a graph to determine if a coordinate pair is a solution to an

equation?

For example, how do you use a graph to determine if (3,2) is a solution to x2 + y2 = 25 ?

In this lesson you will learn how to determine if a

coordinate pair is a solution to an equation by using its graph.

Let’s Review

Graph x2 + y2 = 25 by using a table

X Y

5 0

-5 02 4.6

2 -4.6

3 -4

-3 -4

Core Lesson

The graph of an equation represents all of its solutions.

x + y = 4

(2,2) 2 + 2 = 4

(5,-1) 5 + -1 = 4

(0,4) 0 + 4 = 4

Core Lesson

Is (3,2) a solution to the equation x2 + y2 = 25 ?

(3,2) is not a solution because it does not lie on the curve.

Check: 32 + 22 ≠ 25

Core Lesson

Is (-4,-3) a solution to the equation x2 + y2 = 25 ?

(-4,-3) is a solution because it lies on the curve.

Check: (-4)2 + (-3)2 = 25

In this lesson you have learned how to determine if a

coordinate pair is a solution to an equation by looking at its

graph.

Guided Practice

Determine if the point (-1,2) satisfies the equation 2x + 4 = y by using its graph.

Extension Activities

Describe one extension activity here…

Extension Activities

Describe another extension activity here…

Extension Activities

Describe a third extension activity here if you have a good one…

Quick Quiz

First, graph the equation by making a table. Then, determine if the point lies on the graph.

1) (-1,1) –x + 4y = 5

2) (2,3) x2 + 7 = y