1. The equations in this example are already set equal to "y". Identify the slope and y-intercept in each equation. Remember: y = mx + b, where m = slope and b = y-intercept.
y = 2x + 1
slope = 2
y-intercept = 1
y = -x + 7
slope = -1
y-intercept = 7
2. Graph the lines.
This example used the slope-intercept method of graphing straight lines.
The b-value tells you where the line crosses the y-axis.
The slope, m, tells you the rise over the run.
If you need help graphing lines, see Graphing Linear Equations.
Find the intersection point (where the lines cross).
These lines cross at the point (2,5).
This means the solution to this system is:
Solution: x = 2 and y = 5.
graph1
3. CHECK: Substitute x = 2 and y = 5 into BOTH of the original equations. If your solutions are correct, both equations will be true!
y = 2x + 1
5 = 2(2) + 1
5 = 5 (check)
y = -x + 7
5 = -(2) + 7
5 = 5 (check)