1. Warm-Up
Solve the system by graphing.

2. Notes Solving a System of Equations by Substitution
1. Solve one of the equations for x or y.
- Get x or y by itself.
2. Substitute your new expression from Step 1 into the other equation and solve for the variable.
3. Plug that solved variable into the other equation from Step 1 and solve for the other variable.
4. Check your answers by plugging it into the original equations.

3. Notes Solve the system by substitution. Ex.
The variable x is already by itself.
1) Solve for x or y.
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

4. Notes Solve the system by substitution. Ex.
Now you try.
Solve the system by substitution.
Ex.
The variable y is already by itself.
1) Solve for x or y.
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

5. Notes Solve the system by substitution. Ex.
The variable x is already by itself.
1) Solve for x or y.
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

6. Notes Solve the system by substitution. Ex.
Now you try.
Solve the system by substitution.
Ex.
The variable y is already by itself.
1) Solve for x or y.
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

7. Notes Solve the system by substitution. Ex.
The variable y is already by itself.
1) Solve for x or y.
Step 3
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

8. Notes Solve the system by substitution. Ex.
Now you try.
Solve the system by substitution.
Ex.
The variable x is already by itself.
1) Solve for x or y.
2) Substitute into other equation.
Step 3
3) Plug in answer into other equation.
4) Check answer!

9. Notes Solve the system by substitution. Ex.
The variable x is already by itself.
1) Solve for x or y.
Step 3
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

10. Notes Solve the system by substitution. Ex.
Now you try.
Solve the system by substitution.
Ex.
The variable y is already by itself.
1) Solve for x or y.
Step 3
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

11. Notes Solve the system by substitution. Ex.
The variable y is already by itself.
1) Solve for x or y.
Step 3
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

12. Notes Solve the system by substitution. Ex.
Now you try.
Solve the system by substitution.
Ex.
The variable y is already by itself.
1) Solve for x or y.
Step 3
2) Substitute into other equation.
3) Plug in answer into other equation.
4) Check answer!

13. Class Work
Solve the system by substitution.