Question

Solve using the elimination method. Show your work. If the system has no solution or an infinite number of solutions, state this.
-5x – 7y = 25.5
-2x + 10y = -9

I don't understand this elimination method? help?

Answer 1

10x+14y=-51 (multiply first equation by -2)
-10x+50y=-45 (multiplied by 5)
Now add these equations together:
10x+14y-10x+50y=-51-45
64y=-96
y=-96/64=-1.5
10x=-51-14y=-51+21=-30
x=-30/10=-3

Answer 2

thank you. but how do you know which to eliminate?

Answer 3

there is no difference- the result will be the same. For example, you can multiply first equation by 10, second by 7 and add these equations by eliminatinig y. Its up to you