How to Solve a Simple Linear Equation

Two Methods:Starting with the Variables on Opposite SidesStarting with the Variables on One Side

You need to find out what "x" equals if you have a problem like 7x – 10 = 3x + 6 . This kind of equation is called a linear equation, and it usually has just one variable. This article will walk you through the simple steps.

Method 1
Starting with the Variables on Opposite Sides

  1. Image titled Solve a Simple Linear Equation Step 1
    1
    Look at your problem: 7x - 10 = 3x - 6. A simple linear equation might look like:
  2. Image titled Solve a Simple Linear Equation Step 2Bullet1
    2
    Check the equation for varying terms and constant terms. Varying terms are numbers like "7x" or "3x" or "6y" or "10z," where the number changes depending on what you plug into the variable, or letter. Constant terms are numbers like "10" or "6" or "30," where the number never changes.
    • Usually, equations won't come with varying terms and constant terms lined up on separate sides. In the example above, the left-hand side (LHS) has both varying and constant terms, as does the right-hand side (RHS).
  3. Image titled Solve a Simple Linear Equation Step 2Bullet2
    3
    Prepare to move the numbers around so that the varying terms are on one side and the constant terms are on the side such as in 16x - 5x = 32 - 10 (that equation is solved in example 2). In order to do this, you may have to subtract or add the numbers you want to move from both sides. In the next step, you'll see how to do that in example 1.
    • The equation 16x - 5x = 32 - 10 does have all the varying terms on one side (LHS), while all the constant terms are on the other side (RHS).
  4. Image titled Solve a Simple Linear Equation Step 3Bullet1
    4
    Move the varying terms to one side of the equation. It doesn't matter to which side you move the varying terms.
    • In example 1, 7x - 10 = 3x - 6 can be rearranged by choosing to subtract either (7x) or (3x) from both sides. Choosing to subtract 7x, you have:

      (7x - 7x) - 10 = (3x - 7x) - 6.

      -10 = -4x - 6
  5. Image titled Solve a Simple Linear Equation Step 3Bullet2
    5
    Next, bring all the constant terms onto the other side of the equation. That is: move the constant terms so that they are on the opposite side of the equation from where the varying terms are.
    • We see that -6 must be subtracted from both sides:

      -10 - (-6) = -4x - 6 - (-6).

      -4 = -4x
  6. Image titled Solve a Simple Linear Equation Step 4Bullet1
    6
    Lastly, to find the value of x, simply divide both sides by the coefficient of x. The coefficient of x (or y, or z, or any letter) is the number in front of the varying term.
    • The coefficient of x in -4x is -4. So divide both sides by -4 to get the value of x = 1.
    • Our answer to the equation 7x - 10 = 3x - 6 is x = 1. You can check this answer by plugging 1 back into every "x" variable and seeing if both sides of the equation equal the same number:

      7(1) - 10 = 3(1) - 6

      7 - 10 = 3 - 6

      -3 = -3

Method 2
Starting with the Variables on One Side

  1. 1
    Know that sometimes the varying terms and the constant terms will be separate. Sometimes, half of your work will be done for you. You'll have all the varying terms on one side and all the constant terms on the other side. If this is the case, all you have to do is the following.
  2. Image titled Solve a Simple Linear Equation Step 5Bullet1
    2
    Simplify both sides. For the equation 16x - 5x = 32 - 10, we just have to subtract the numbers from one another.
  3. Image titled Solve a Simple Linear Equation Step 5Bullet2
    3
    Next, divide both sides by the coefficient of x. Remember that the coefficient of x is the number in front of the varying term.
    • In this example, the coefficient of x in 11x is 11. that division is 11x ÷ 11 = 22 ÷ 11 to get x = 2. The answer to the equation 16x - 5x = 32 - 10 is x = 2.

Warnings

  • Why do it that way? Trying to divide this:

    4x - 10 = - 6 like this 4x/4 - 10/4 = -6/4 creates x - 10/4 = -6/4 with a lot of fractions to handle, and that's not so easily solved; so, simplifying is one good reason to get all the variable terms onto one side and all the constant terms onto the other side.

Article Info

Categories: Algebra