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

@jameshorton

Answer 2

how many question you have

Answer 3

just 7 more

Answer 4

but this answer is B

Answer 5

In step 2 they did not simplify right. They multiplied the -2 to the y but not the entire equation.

Answer 6

y = 15 – 2z

–2y = –2•( 15 – 2z )

Answer 7

yh and i think it would cancel out z and y