1. Systems of Equations By Substitution and Elimination

2. SUBSTITUTION When to use: If one variable is already alone, or if it is easy to solve for a variable.

3. Steps 1.Solve for a variable. 2.Substitute into other equation. 3.Solve. 4.Plug answer into either equation to solve for other variable.

4. Example 1

5. You try!

6. ELIMINATION When to use: When equations are in standard form (Ax+By=C)

7. Solving a system of equations by elimination using multiplication. Step 1: Put the equations in Standard Form. Step 2: Determine which variable to eliminate. Step 3: ADD the equations and solve. Step 4: Plug back in to find the other variable. Step 5: Check your solution. Standard Form: Ax + By = C Look for variables that have the same coefficient. If there is none, multiply by a constant. Solve for the variable. Substitute the value of the variable into the equation. Substitute your ordered pair into BOTH equations.

8. Example 1

9. You try!

10. Homework