3x - y = 6 and y = x - 4, use addition to solve the linear system of equations.

Alright, so I'm trying to figure this out, at first I made y = x - 4 into x - y = 4, then thought I could've gotten it wrong and made it into - x + y = 4. In that one, trying to add the two equations together got me - 4x = 2, 2/4 = 0.5 and I already know x = 1 and y = - 3, but I just don't understand how to get there?

Question

Mathematics

Jonas Sampson

23 May, 00:07

3x - y = 6 and y = x - 4, use addition to solve the linear system of equations.

Alright, so I'm trying to figure this out, at first I made y = x - 4 into x - y = 4, then thought I could've gotten it wrong and made it into - x + y = 4. In that one, trying to add the two equations together got me - 4x = 2, 2/4 = 0.5 and I already know x = 1 and y = - 3, but I just don't understand how to get there?

+1

Answers (1)

Know the Answer?

Gunnar Lang · Answer 1

3x-y=6

y=x-4

solve by substitution

3x-x+4=6

2x=2

x=1

Now that you know x, but in in the equation to find y (either equation will work)

y = 1-4

y = - 3

now that you have both answers, let's check them.

3 (-1) - (-3) = 6

yes, it works ...

Hopefully this makes sense!