Question

The system of equations can be solved using linear combination to eliminate one of the variables.

2x − y = −4 → 10x − 5y = −20
3x + 5y = 59 → 3x + 5y = 59
13x = 39
Which equation can replace 3x + 5y = 59 in the original system and still produce the same solution?

2x – y = –4
10x – 5y = –20
7x = 39
13x = 39

Answer 1

13x = 39

Reason: 13x = 39 is obtained by adding 5 times (2x − y = −4) to (3x + 5y = 59). Replacing the second equation with that sum is an elementary row operation and preserves the solution set.