Algebra 2 Companion Book, Volume 1

3.1.2 Using Algebraic Methods to Solve Linear Systems - Worksheet

Example 1: Use substitution to solve each system of equations. 1. 2. = − y x 19 3.

4.

  

  

  

  

− = − = 2 3 2 11 x y x y 2

y x x y

x y y x

= + =− − 3 5

17 7

+ = = +

x y

3 5

2

27

− =

Example 2: Use elimination to solve each system of equations. 5. + = − − =−    x y x y 2 12 5 33 6. − =− − + =−    x y x y 2 5 5 2 8 58

+ = − − =−      x y x y 1 2

7.

8.

  

+ =− − = 2 6 8 5 3 88 x y x y

4 2 2 6

Example 3: Classify each system and determine the number of solutions. 9. − =− − =− x y x y 5 3 15 3 9 10. − =− = − x y x y 2 8 4 8 56 11. + = + =− x y x y 8 12 60 2 3 24         

    

− =− x y 1 3 2 6 2 12 − =− x y

12.

Example 4: 13.  Denise owns a car that runs on a mixture of gasoline and ethanol. She can buy fuels that have 85% ethanol or 25% ethanol. How much of each type of fuel should she buy if she wants to fill her 20 gal tank with a mixture of fuel that contains 50% ethanol?

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