Question

The solution to the system of equation below is (−2, −1).

2x − 3y = −1
11x − 9y = −13

When the first equation is multiplied by −3, the sum of the two equations is equivalent to 5x = −10.

Which system of equations will also have a solution of (−2, −1)?


5x = −10
11x − 9y = −13


2x + 9y = −1
11x − 9y = −13


−6x + 9y = −1
11x − 9y = −13

Answer 1

The first system:

5x = −10
11x − 9y = −13

Check: 5(−2) = −10 and 11(−2) − 9(−1) = −22 + 9 = −13, so (−2, −1) satisfies both. The other two do not (2(−2)+9(−1)=−13 ≠ −1; −6(−2)+9(−1)=3 ≠ −1).