Question

The work of a student trying to solve the equation 3(4x − 2) = 9 + 2x + 5 is shown below:

Step 1: 3(4x − 2) = 9 + 2x + 5
Step 2: 12x − 2 = 14 + 2x
Step 3: 12x − 2x = 14 + 2
Step 4: 10x = 16
Step 5: x = 1.6

In which step did the student first make an error and what is the correct step?

Answer 1

The error is in step 2
3*-2 =-6 when distributing

Here is how to solve it correctly
3(4x − 2) = 9 + 2x + 5
12x-6=14+2x
(add 6 to both sides of the equations, the -6 gets canceled out)
12x=20+2x
10x=20
x=2