Solving Systems of Equations

What is a System of Equations?

A system of equations is a set of two or more equations with the same variables. The solution to a system of equations is the point where the graphs of the equations intersect.

Methods to Solve a System of Equations:

1. Substitution Method

First, solve one equation for one variable and substitute it into the other equation.

2. Elimination Method

Next, add or subtract the equations to eliminate one variable, then solve for the remaining variable.

3. Graphical Method

Finally, graph both equations and find the point where they intersect, which is the solution to the system.

Example 1: Substitution Method

Solve the system of equations:

1) 2x + 3y = 6
2) x - y = 1

Solution (Substitution Method):

            Step 1: Solve the second equation for x.
            x = y + 1

            Step 2: Substitute x = y + 1 into the first equation.
            2(y + 1) + 3y = 6
            2y + 2 + 3y = 6
            5y = 4
            y = 4/5

            Step 3: Substitute y = 4/5 into x = y + 1 to find x.
            x = 4/5 + 1
            x = 9/5
            

Example 2: Elimination Method

Solve the system of equations:

1) 3x + 4y = 12
2) 2x - 4y = 4

Solution (Elimination Method):

            Step 1: Add the two equations to eliminate y.
            (3x + 4y) + (2x - 4y) = 12 + 4
            5x = 16
            x = 16 / 5

            Step 2: Substitute x = 16/5 into one of the original equations.
            3(16/5) + 4y = 12
            48/5 + 4y = 12
            4y = 12 - 48/5
            4y = 60/5 - 48/5
            4y = 12/5
            y = 3/5
            

Example 3: Graphical Method

Graph the system of equations:

1) y = 2x + 1
2) y = -x + 4

Solution (Graphing Method):

Plot both equations on a graph and find the point where they intersect. The intersection point is the solution to the system.

For this system, the graphs intersect at (1, 3).

Try Solving It Yourself:

Now, try solving this system of equations:

1) 4x + 2y = 8
2) 3x - y = 3
Click here for the solution