Study Guide

Basic Algebra - Solving Two-Step Equations

Solving Two-Step Equations

Solving two-step equations isn't much more complicated than solving one-step equations; it just involves an extra step.

Usually, there's more than one way to solve these. It's okay to use whatever method makes the most sense to you. The general rule of thumb when isolating the variable is to undo the order of operations, PEMDAS. Start with addition and subtraction, then multiplication and division, then exponents, and finally parentheses.

Let's look at an example:

Solve 2x - 6 = 12 for x.

Method 1

2x-6=12
2x -6 +6 = 12 + 6add 6 to each side
2x = 18
2x/2=18/2divide each side by 2
x=9

Method 2

2x -6 = 12
(2x-6)/2= 12/2divide each side by 2
2x/2 - 6/2 =12/2separate the fractions
x - 3 = 6simplify
x - 3 + 3 = 6 + 3add 3 to each side
x=9

Check the answer:

2(9) - 6 = 12

18 - 6 = 12

12 = 12

w00t!

Personally, we think that the first method is easier, since we don't need to worry about separating the fractions. It's also the method that follows the rule the best, and first gets rid of the least connected number (the 6).

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