- #1
DrummingAtom
- 659
- 2
I know this is a simple question but I can't exactly figure out the logic governing this problem, I just know it had to be this way. Let's say I have two equations:
x - 4y + 9 = 0
y - 3x + 5 = 0
If I set them equal to each other then I get no where because I'll have both x and y in the answer. But if I solve one of them for x or y then plug it into the other I can isolate one of them and then get an answer for x and y. Then by re-substitution I'll get answers for both x and y.
The only way setting them equal to each other would work is if x or y had values that canceled during that time which in this case they don't. Is there a mathematical logic rule governing this? Or is it just by practice we know it has to be done this way? Thanks
x - 4y + 9 = 0
y - 3x + 5 = 0
If I set them equal to each other then I get no where because I'll have both x and y in the answer. But if I solve one of them for x or y then plug it into the other I can isolate one of them and then get an answer for x and y. Then by re-substitution I'll get answers for both x and y.
The only way setting them equal to each other would work is if x or y had values that canceled during that time which in this case they don't. Is there a mathematical logic rule governing this? Or is it just by practice we know it has to be done this way? Thanks