Question

The work of a student to solve a set of equations is shown:

Equation A: y = 15 – 2z
Equation B: 2y = 3 – 4z

Step 1: –2(y) = –2(15 – 2z) [Equation A is multiplied by –2.]
2y = 3 – 4z [Equation B]
Step 2: –2y = 15 – 2z [Equation A in Step 1 is simplified.]
2y = 3 – 4z [Equation B]
Step 3: 0 = 18 – 6z [Equations in Step 2 are added.]
Step 4: 6z = 18
Step 5: z = 3
In which step did the student first make an error?


Step1
Step 2
Step 3
Step 4

Answer 1

Option: step 2.

Because the student divided only the right side by 2. If you divide one side by a number you have to do the same with the other side to maintain the equality.