GOZUNTA
Try it now
All courses Math I · A-REI.3 9 of 59
Solve linear equations and inequalities in one variable, including literal linear equations.

Solve a one- or two-step linear equation

Problem
Solve the linear equation 3x + 4 = 19.
Your answer
With a free account

Keep complete walkthroughs close.

Every problem included with your account keeps its hints and full solution walkthrough available for review.

Create a free account
With paid access

Make a more precise practice set.

Choose from the complete range of objectives and problem types in your subscribed course when building a session.

Compare plans

Hint

Undo the +4 first by subtracting 4 from both sides.

After subtracting 4, divide both sides by 3 to isolate x.

Solution walkthrough

01

Start with the equation

\[3x~+~4~=~19\]

The goal is to get x by itself.

02

Undo the addition

\[3x~=~15\]

Subtract 4 from both sides to remove the constant term attached to 3x.

03

Solve for x

\[x~=~5\]

Divide both sides by 3 to isolate x.

04

Check the solution

\[3(5)~+~4~=~19\]

Since 15 + 4 = 19, the solution x = 5 is correct.

+

Another way

  1. You can think of 19 as 4 more than a multiple of 3, so removing 4 gives 15 and then 15 divided by 3 is 5.

!

Common mistake

A common mistake is to divide 19 by 3 before removing the +4. The addition must be undone before the multiplication by 3.