How do you do the elimination method for 8x-y20 and -5x y-8?

Answer 1

If this is:

8x - y = 20

-5x = y - 8

8x - y = 20

-5x - y = -8 multiply by -1in order to eliminate y;

8x - y = 20

5x + y = 8 add both equations;

13x = 28

x = 28/13 substitute the value of x into the one of the equations in order to find y. For example, substitute it into the first one;

8(28/13) - y = 20

224/13 - y = 20 multiply both sides with 13;

224 - 13y = 260

224 - 224 - 13y = 260 - 224

-13y = 36 multiply both sides by -1;

13 y = -36 divide both sides by 13;

y = -36/13

So the solution set is (28/13, -36/13)

Check:

8(28/13) -(-36/13)= 224/13 + 36/13 = 260/13 = 20

-5(28/13) = -36/13 - 8 ?

-140/13 = -36/13 -8 ?

-140/13 = -36/13 - 8(13/13) ?

-140/13 = -36/13 - 104/13 ?

-140/13 = -140/13