Pre-Algebra Demystified

Math Note: To check, substitute the values of x and y for the

solution in both equations and see if they are closed true equations.

EXAMPLE

Find the solution of:

3x
y¼ 8

xþ2y¼ 5

SOLUTION

Find two points on each line. For 3x
y¼8, use (2,
2) and (4, 4). For
xþ2y¼5, use (7,
1) and (1, 2). Graph both lines and then find the point of
intersection (see Fig. 11-28).

The point of intersection is (3, 1).

PRACTICE
Find the solution for each of the following system of equations:

1. x
   y¼ 4
   xþy¼ 10

CHAPTER 11 Graphing 227

Fig. 11-28.