Question

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

equation a: y = 4 – 2z
equation b: 6y = 2 – 4z


step 1: –6(y) = –6(4 – 2z) [equation a is multiplied by –6.]
6y = 2 – 4z [equation b]
step 2: 6y = 4 – 2z [equation a in step 1 is simplified.]
6y = 2 – 4z [equation b]
step 3: 0 = 6 – 6z [equations in step 2 are added.]
step 4: 6z = 6
step 5: z = 1


in which step did the student first make an error?
step 4
step 3
step 2
step 1

Answer 1

That would be step 2.

step 1 is correct....multiplying the first equation by -6 which gives you :
-6y = -24 + 12z
but in step 2, the simplifying would be : y = 4 - 2z