Question

The work of a student trying to solve the equation 2(4x − 3) = 9 + 2x + 6 is shown below: Step 1: 2(4x − 3) = 9 + 2x + 6 Step 2: 8x − 3 = 15 + 2x Step 3: 8x − 2x = 15 + 3 Step 4: 6x = 18 Step 5: x = 3 In which step did the student first make an error and what is the correct step? (4 points) a Step 2: 8x − 3 = 15 + 2x b Step 2: 8x − 6 = 15 + 2x c Step 3: 8x + 2x = 15 + 2 d Step 3: 8x − 2x = 15 − 2

Answer 1

Explanation:

2(4x - 3) = 9 + 2x + 6 Combine the like terms on the right

2(4x - 3) = 2x + 15 The distributive property gets rid of the brackets

8x - 6 = 2x + 14 Add 6 to both sides

6 6

8x = 2x + 20 Subtract 2x from both sides

-2x -2x

6x = 20

Step 2 is the error. It is a very common error. You multiply 2 and - 3 together. as well as 2 and 4 together. If you are going to forget something that will be it.