GED Practice

GED Math Review: Solving Systems by Substitution


Questions:

A. Solve each system by substitution. Check your answer.


  1. x + y = 3
    2x + 4y = 8

    Solution: __________
  2. x + 2y = 7
    4x + 3y = 3

    Solution: 
    __________
  3. -4x + y = 3
    5x - 2y = -9

    Solution: __________
  4. 8x - 7y = -2
    -2x - 3y = 10

    Solution: __________
  5. 2x - 2y = 5
    4x - 4y = 9

    Solution: __________
  6. 2x + 7y = 2
    4x + 2y = -2

    Solution: __________
  7. 2x - y = 7
    2x + 7y = 31

    Solution: __________
  8. x - 2y = -4
    4y = 2x + 8

    Solution: __________

    B. Tell whether it is more efficient to solve for x and then substitute for x or to solve for y and then substitute for y. Explain your reasoning. Then solve the system.
  9. 9x - 3y = 15
    x + 3y = -8

    ______________________________________
    ______________________________________
    Solution: __________
  10. x/2 + y = 6
    x/4 + y/2 = 3

    ______________________________________
    ______________________________________
    Solution: __________
Answers:

  1. (2, 1)
  2. (-3, 5)
  3. (1, 7)
  4. (-2, -2)
  5. no solution
  6. (-3/4, 1/2)
  7. (5, 3)
  8. infinitely many solutions
  9. (1, -3)
  10. infinitely many solutions







Reference:




Complete Test Preparation for the GED Test 2014 by Steck-Vaughn