Question

Question 4 Unsaved

(05.02 LC)
Given the system of equations presented here:

2x + 4y = 14
4x + y = 20

Which of the following actions creates an equivalent system such that, when combined with the other equation, one of the variables is eliminated? (5 points)

Question 4 options:

1)

Multiply the second equation by −4 to get −16x − 4y = −80

2)

Multiply the second equation by −1 to get −4x − y = −20

3)

Multiply the first equation by 2 to get 4x + 8y = 28

4)

Multiply the first equation by −1 to get −2x − 4y = −14

Answer 1

The 1st selection is appropriate.

The result will be equations with y-coefficients of +4 and -4, which will cancel when they are added.

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If you do the exercise of selection (3), you get x-coefficients of +4 and +4. You can "combine" these by subtracting one from the other to cancel x-terms. This may also be a viable answer to the question, but you might need to argue the meaning of "combined."