Use the Slope–Intercept Form of an Equation of a Line: example 4.47

Graph the line of the equation $y = 0.2 x + 45$ using its slope and y-intercept.

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Graph the line of the equation $y = 0.5 x + 25$ using its slope and y-intercept.

How did it go?

	$y = m x + b$
The equation is in slope–intercept form.	$y = 0.2 x + 45$
Identify the slope and y-intercept.	$m = 0.2$
	The y-intercept is (0, 45)
Plot the y-intercept.	See graph below.
Count out the rise and run to mark the second point. The slope is $m = 0.2$ ; in fraction form this means $m = \frac{2}{10}$ . Given the scale of our graph, it would be easier to use the equivalent fraction $m = \frac{10}{50}$ .
Draw the line.

	$y = m x + b$
The equation is in slope–intercept form.	$y = 0.2 x + 45$
Identify the slope and y-intercept.	$m = 0.2$
	The y-intercept is (0, 45)
Plot the y-intercept.	See graph below.
Count out the rise and run to mark the second point. The slope is $m = 0.2$ ; in fraction form this means $m = \frac{2}{10}$ . Given the scale of our graph, it would be easier to use the equivalent fraction $m = \frac{10}{50}$ .
Draw the line.