Question

Michael solved the system of linear equations and provided the solution.

3x – 3y = 6
4x – 7y = 2


Step 1 4(3x – 3y = 6)
–3(4x – 7y = 2)
Step 2 12x – 12y = 24
–12x + 21y = –6
Step 3 9y = 18
Step 4 y equals 1 over 2

In which step did Michael show his first error?
Step 2
Step 3
Step 4
No errors are present in the solution

Answer 1

Answer:

  Step 4

Step-by-step explanation:

You want to know the first step that has an error in Michael's solution of the system of equations ...

• 3x -3y = 6
• 4x -7y = 2

Elimination

Michael correctly subtracts 3 times the second equation from the first to eliminate the x-variable and get ...

  9y = 18 . . . . . . . step 3

Michael incorrectly divides this equation by 9. His result should be ...

  y = 18/9 = 2 . . . . . correct step 4

Michael's step 4 shows his first error.

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Additional comment

The correct solution is (x, y) = (4, 2).