2-2 Solving Two-Step Equations

Objective

To solve two-step equations in one variable

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The problem in the Solve It can be modeled by an equation. The equations in this lesson are different from the equations in Lesson 2-1 because they require two steps to solve.

Essential Understanding To solve two-step equations, you can use the properties of equality and inverse operations to form a series of simpler equivalent equations. You can use the properties of equality repeatedly to isolate the variable.

A two-step equation, like the one shown below, involves two operations.

Multiplication ▼ 2 x + 3 = 15 ▲ Addition table with 5 rows and 1 column , row1 column 1 , begin box , cap multiplication , end box , row2 column 1 , black down pointing triangle , row3 column 1 , 2 x plus 3 equals 15 , row4 column 1 , black up pointing triangle , row5 column 1 , begin box , cap addition , end box , end table

To solve a two-step equation, identify the operations and undo them using inverse operations. You can undo the operations in the reverse order of the order of operations. For example, to solve 2x + 3 = 15, you can use subtraction first to undo the addition, and then use division to undo the multiplication.

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