4. Writing Equations in Two Variables
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Make a function table to obtain ordered pairs.
To graph the function y=2x+4, 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 | 2x+4 | y | (x,y) |
---|---|---|---|
0 | 2( 0)+4 | 4 | ( 0, 4) |
1 | 2( 1)+4 | 6 | ( 1, 6) |
2 | 2( 2)+4 | 8 | ( 2, 8) |
3 | 2( 3)+4 | 10 | ( 3, 10) |
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=2x+4.