Example: Graph y = −2x + 6 by plotting five points.
Step 1: Choose any five x-values.
Step 2: Evaluate to find the corresponding y-values.
Step 3: Plot the points and use a straight edge to draw a line through them.
When choosing x-values it is wise to pick some negative numbers as well as zero. Try to find the points where the line crosses the x and y axes. These special points are called the x- and y-intercepts.
Is the given point a solution?
Remember that we are less likely to make a mistake if we insert parentheses where we see a variable and then substitute in the appropriate values.
Find the corresponding value.
Graph by plotting points.
Example: Graph y = 2x − 4 by plotting five points.
Example: Graph y = −x − 2 by plotting five points.
Choosing a scale when creating a blank coordinate system will take some thought. Keep in mind that the scale on the x-axis need not be the same as the scale on the y-axis.
Example: Graph y = 1/2 x − 6 by plotting five points.
When the coefficient of x is a fraction, choose x-values to be multiples of the denominator so that you might avoid unnecessarily tedious calculations.
Example: Graph y = −3/2 x + 6 by plotting five points.
Example: Graph 2x − 3y = 6 by plotting five points.
When dividing a binomial by a number you must divide both terms by that number. For example, treat the −3 as a common denominator as in the previous problem.
A common error is to just divide the 6 by −3.
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