Question

a student is using the elimination method to solve the system of equations below. what is the best first step?

5x - 2y = -15
3x 3y = 12

1. multiply the first and second equation by 3.
2. multiply the first equation by 3 and the second equation by 2.
3. multiply the first equation by 2 and the second equation by 3.
4. multiply the first equation by 5 and the second equation by 3.

Answer 1

The best first step for the elimination method would be 2. multiply the first equation by 3 and the second equation by 2.

5x - 2y = -15     /*3
3x + 3y = 12     /*2
____________
15x - 6y = -45
6x + 6y = 24
____________
15x - 6y + 6x + 6y = -45 + 24
21x = -21
x = -1