Writing and Solving Two-Step Equations

Concept

One- and Two-Step Equations

Equations can be named according to the minimum number of inverse operations needed to solve them.

One-Step Equations

A one-step equation is an equation that needs only one inverse operation to be solved. Below is an example of a one-step equation. x+4=9 This equation can be solved by subtracting 4 from both sides.

x+4=9
x+4- 4=9- 4
x=5

Two-Step Equations

A two-step equation is an equation that needs two inverse operations to be solved. Below is an example of a two-step equation. 2x-3=11 This equation can be solved by first adding 3 to both sides and then dividing both sides by 2.

2x-3=11
2x-3+ 3=11+ 3
2x=14
2x/2=14/2
2/2x=14/2
1x=7
x=7

Note that the steps taken to undo each operation are performed in reverse order. This means that the second operation applied to the variable is undone first. Next, the first operation applied to the variable is then undone.

Exercises
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