69.7k views
5 votes
The work of a student to solve the equation 2(4x − 4) = 8 + 4x + 4 is shown below: Step 1. 2(4x − 4) = 8 + 4x + 4 Step 2. 6x − 6 = 12 + 4x Step 3. 6x − 4x = 12 + 6 Step 4. 2x = 18 Step 5. x = 9 In which step did the student first make an error and what is the correct step? Step 2, 8x − 6 = 2(6 + 2x + 2) Step 2, 8x − 8 = 12 + 4x Step 3, 6x − 4x = 12 − 6 Step 3, 6x + 4x = 12 + 6

User Pointer
by
8.1k points

1 Answer

3 votes

Answer is step 2, 8x - 8= 12 + 4x

The student did not distribute the 2 into the parentheses properly which ruined their entire problem. With 2(4x-4) , you must multiply everything in parentheses by 2.

so 2 x 4x = 8x

2 x -4 = -8

making it 8x- 8 = 12 + 4x ( on the right side all you did was combine like terms)

User Lokesh Paunikar
by
8.1k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories