APS edu service

1. Solving simultaneous
equations graphically

2. The Question:
y = 2x + 1
y=4-x
Solve the simultaneous equations graphically.

3. y = 2x + 1 y=4-x
Begin by constructing a table of values:
y = 2x + 1
x -2 0 2 4
y -3 1 5 9
Use the equation to fill in the y value when x = -2
Now fill in the rest of the table

4. y = 2x + 1 y=4-x
Use the
y = 2x + 1 table to draw
x -2 0 2 4 the graph of
y -3 1 5 9 the equation.
10 y
8
6
4
2
0
-3 -2 -1 0 1 2 3 4 5
x
-2
y = 2x + 1 -4

5. y = 2x + 1 y=4-x
Now construct a second table of values:
Y=4-x
x -2 0 2 4
y 6 4 2 0
Plot this line on the axes you used earlier...

6. 10 y
8
y=4-x 6
4
2
0 x
-3 -2 -1 0 1 2 3 4 5
-2
y = 2x + 1 -4
The solution is where the 2 lines cross:
Read the x-value from the x-axis... 1
Now read off the y-value... 3

7. So the solution of y = 2x + 1 and
y = 4 - x is...
x=1 and y=3