Question

The work of a student to solve the equation 4(2x − 4) = 8 + 2x + 8 is shown below: Step 1: 4(2x − 4) = 8 + 2x + 8 Step 2: 6x − 8 = 16 + 2x Step 3: 6x − 2x = 16 + 8 Step 4: 4x = 24 Step 5: x = 6 In which step did the student first make an error and what is the correct step? (5 points) Step 2; 8x − 4 = 2(6 + x + 6) Step 2; 8x − 16 = 16 + 2x Step 3; 6x − 2x = 16 − 8 Step 3; 6x + 2x = 16 + 8

Answer 1

He made his mistake on step 2
Correct next step is 8x-16=16+2x
Add 16 on both sides
You get 8x=32+2x
Then subtract 2x on both sides
You get 6x=32
Divide by 6 on both sides
Left with x=5.3 repeated or 16/3