4. Writing Equations in Two Variables
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Make a function table to obtain ordered pairs.
To graph the function y=3x, we will follow two steps.
To make a function table, we will select some values of x. 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 | 3x | y | (x,y) |
|---|---|---|---|
| 0 | 3( 0) | 0 | ( 0, 0) |
| 1 | 3( 1) | 3 | ( 1, 3) |
| 2 | 3( 2) | 6 | ( 2, 6) |
| 3 | 3( 3) | 9 | ( 3, 9) |
We found four ordered pairs that lie on the graph of our function.
Next, we will graph the ordered pairs and connect them with a straight 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=3x.