Question

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

Equation 1: m = 6 + n
Equation 2: 2m = 8 + 8n


Step 1: −2(m) = −2(6 + n)
2m = 8 + 8n

Step 2: −2m = −12 − 2n
2m = 8 + 8n

Step 3: −12 − 2n = 8 + 8n

Step 4: −20 = 10n

Step 5: n = −2


In which step did the student first make an error?
Step 2
Step 3
Step 4
Step 5

Answer 1

Step 3, sorry do not have time to explain. The explanation above is helpful though sorry again.

Answer 2

if you would like to know in which step did the student first make an error, you can find this using the following steps:

m = 6 + n
2m = 8 + 8n
________________
-2(m) = -2(6+n)
2m = 8 + 8n
________________
-2m = -12 - 2n
2m = 8 + 8n
________________
-12 - 2n = - (8 + 8n) ... Step 3
-12 - 2n = -8 - 8n
- 2n + 8n = -8 + 12
6n = 4
n = 4/6 = 2/3

The correct result would be: Student made an error in Step 3.