The work of a student to solve a set of equations is shown:
equation a: y = 4 − 2z
equation b: 4y = 2 − 4z
step 1:
−4(y) = −4(4 − 2z) [equation a is multiplied by −4.]
4y = 2 − 4z [equation b]
step 2:
−4y = 4 − 2z [equation a in step 1 is simplified.]
4y = 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 1
step 3
step 4
step 2