Mathematics

Derek Stein

30 August, 01:17

Mark is solving the following system.

x+y+z=2 (1)

3x+2y+z=8 (2)

4x-y-7z=16 (3)

Step 1: He multiplies equation (1) by 7 and adds it to equation (3).

Step 2: He multiplies equation (3) by 2 and adds it to equation (2).

Which statement explains Mark's mistake?

- He added equation (3) instead of equation (2) in step 1.

- He did not multiply equation (3) by the correct value.

- He did not eliminate the same variables in steps 1 and 2.

- He added equation (3) and equation (2) instead of subtracting.