How do you use the substitution method in math?

posted by .

x + 6 / 7 = 6x + 78 / 49

My mind is a bit rusty and I can't remember how to use this method

  • How do you use the substitution method in math? -

    The 'substitution method' is used when you have two equations in two variables.

    It is only practical if one of the equations is set up so that you can easily solve for one of the variables in terms of the other.
    You would then "substitute" that into the other equation.

    In your case you only gave one equation.
    Did you want to solve for x??

    if so, then multiply each term by 49 to eliminate the fractions

    49x + 42 = 294x + 78
    -36 = 245x
    x = -36/245

    Since you did not supply any brackets to change the order of operation, that would be the correct answer the way you wrote the question.

  • How do you use the substitution method in math? -

    Example:

    2y + x = 3
    (1)

    4y – 3x = 1
    (2)


    Equation 1 looks like it would be easy to solve for x, so we take it and isolate x:

    2y + x = 3


    x = 3 – 2y
    (3)


    Now we can use this result and substitute 3 - 2y in for x in equation 2:



    Now that we have y, we still need to substitute back in to get x. We could substitute back into any of the previous equations, but notice that equation 3 is already conveniently solved for x:



    And so the solution is (1, 1).

    As a rule, the substitution method is easier and quicker than the addition method when one of the equations is very simple and can readily be solved for one of the variables.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. math

    Systems of equations can be solved by graphing or by using substitution or elimination. What are the pros and cons of each method?
  2. Math

    12x+4y= 22 and 3x-8y= -10 What are the coordinates of x and y?
  3. Algebra

    Systems of equations can be solved by graphing or by using substitution or elimination. What are the pros and cons of each method?
  4. MATH

    SYSTEMS OF EQUATIONS CAN BE SOLVED BY GRAPHING OR BY USING SUBSTITUTION OR ELIMINATION. WHAT ARE THE PROS AND CONS OF EACH METHOD?
  5. math

    SYSTEMS OF EQUATIONS CAN BE SOLVED BY GRAPHING OR BY USING SUBSTITUTION OR ELIMINATION. WHA ARE THE PROS AND CONS OF EACH METHOD?
  6. algebra

    "Systems of equations can be solved by graphing or by using substitution or elimination. What are the pros and cons of each method?
  7. algebra

    o Systems of equations can be solved by graphing or by using substitution or elimination. What are the pros and cons of each method?
  8. math substitution method

    use the substitution method to solve 7x+5y=-26 x=28-6y
  9. algebra

    use the Substitution Method. Please give it a try. y = 3x + 4 5x + 3y = 12 Why is the substitution method preferred in this case?
  10. Algebra 1

    bobpursey, In this problem you helped me with earlier: Solve using any appropriate method. y = 2× - 5, y = ½× + 1 Substitution, substitute for y. 2×-5=½ × + 1 3/2 x=6 x=4 y= 2*4-5=3 How did you choose which method you were going …

More Similar Questions