Pre-Algebra Demystified

Let x 1 ¼ 4 ;y 1 ¼
5 and x 2 ¼
2, y 2 ¼10. Now substitute in the slope

formula:

m¼

y 2 
y 1

x 2 
x 1

m¼

10 
ð
 5 Þ


 2 
 4

¼

15

6

¼

5

2

The slope of the line 5xþ2y¼10 is
^52.

Another way to find the slope of a line is to solve the equation for y in

terms of x. The coefficient of x will be the slope.

EXAMPLE

Find the slope of a line whose equation is 5xþ2y¼10.

SOLUTION

Solve the equation for y, as shown:

5xþ2y¼ 10

5x
5xþ2y¼
5xþ 10

2y¼
5xþ 10

2 y

2

¼

5x

2

þ

10

2

y¼

5

2

xþ 5

Hence, the slope is
^52 , which is the result found in the previous example.

Math Note: An equation in the form of y in terms of x is called the

slope–intercept form and in general is written as y¼mxþb, where m

is the slope and b is the y intercept.

224 CHAPTER 11 Graphing