Answer:
x = -2, y = 21
Step-by-step explanation:
Let 4x + y = 13 to be equation1 {eqn1}
and let 5x - y = 5 to be equation2 {eqn2}
Using elimination method, you would try to make sure a particular unknown has the same value in both equation 1 and 2. This would make it easy for you to subtract one equation from the other.
Notice how the value of y is the same in both equations. That's a good sign.
But the signs aren't the same. Meaning y in eqn1 has a value of +1, and y in eqn2 has a value of -1. We need to make them similar.
So, we multiply the value of y in eqn1 by all the terms in eqn2. And, do pretty much the same thing by multiplying the value of y in eqn2 by all the terms in eqn1.
You would have:
-1 * (4x + y = 13)
+1 * (5x - y = 5)
This would result in;
-4x - y = -13 (eqn3)
5x - y = 5 (eqn4)
So, just subtract eqn3 from 4
You would have;
(5x - -4x) + (-y -- y) = (-13 - 5)
9x + 0 = -18
x = -18/9 = -2
and to find y;
just substitute the value of x into any of the 4 equations. let's try equation 1
Therefore;
4(-2) + y = 13
-8 + y = 13
y = 13 + 8 = 21
