The work of a student to solve the equation 4(3x − 4) = 8 + 4x + 8 is shown below: Step 1. 4(3x − 4) = 8 + 4x + 8 Step 2. 7x − 8 = 16 + 4x Step 3. 7x − 4x = 16 + 8 Step 4. 3x = 24 Step 5. x = 8 In which step did the student first make an error and what is the correct step? A. Step 2, 12x − 16 = 16 + 4x B. Step 2, 12x − 8 = 2(4 + 2x + 4) C. Step 3, 7x − 4x = 16 − 8 D. Step 3, 7x + 4x = 16 + 8

Question

Answer:

4(2x − 4) = 8 + 2x + 8
Distribute 4:
8x - 8 = 8 + 2x + 8 ← Error here, she wrote as 6x - 8 = 8 + 2x + 8
8x - 8 = 2x + 16
8x - 2x = 16 + 8
6x = 24
x = 6
Answer: Step 2; 8x − 16 = 16 + 2x

solved

general 11 months ago 1418