Big Ideas Math: Modeling Real Life, Grade 8
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5. Analyzing and Sketching Graphs
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Exercise 3 Page 305

First, apply inverse operations to isolate y. Then, make a function table to obtain ordered pairs to graph the equation.

Practice makes perfect
To solve the given linear equation for y, we will use the Properties of Equality to apply inverse operations on the equation. Remember, only like terms can be combined.
-4x+y=-1
â–Ľ
Solve for y
-4x+y+4x=-1+4x
y=-1+4x
y=4x-1
Now, we will follow two steps to graph the equation y=4x-1.
  1. Make a function table to obtain ordered pairs.
  2. Graph the ordered pairs and draw the line through them.

Let's do these things one at a time.

Making a Function Table

To make a function table, we will select some values of x which will be part of our domain. Then, we will substitute these values for x to find the corresponding values of y. These x- and y-values will create a set of ordered pairs.

x 4x-1 y (x,y)
- 1 4( - 1)-1 -5 ( - 1, -5)
0 4( 0)-1 -1 ( 0, -1)
1 4( 1)-1 3 ( 1, 3)

We found three ordered pairs that lie on the graph of our function.

Graphing the Ordered Pairs and Drawing the Line

Next, we will graph the ordered pairs and connect them with a straight line.

points and line

The line is the complete graph of the function. The ordered pairs corresponding to any points on the line are solutions of the equation y=4x-1.