Help with an 'impossibly' easy math question

[Zageron]

Root word damnit.

-x - 2----y + 1
------ + ------ = 2
--3---------5


x + 2----y + 5
------ - ------ = -2
--7--------3

Solve the system of equations.

I've worked through an entire math class, and 30 minutes just now. Trying to figure it out. I can't get it.
(Teacher was away so i couldn't ask for help, I got help from friends but we couldn't figure out what I was doing wrong...)

Gr. 11P math

Please help.

Thanks,

Edit: BY THE WAY
There are no decimals or Fractions in the answer.

[travman301]

Re: Help with an 'impossibly' easy math question

X=5, y=4

Edit: Looks like I win. ^_^

[Gano]

Re: Help with an 'impossibly' easy math question

math is my bane

[pntballa18]

Re: Help with an 'impossibly' easy math question

rofl how is that hard, did it in my head and got the same as trav

[Zageron]

Re: Help with an 'impossibly' easy math question

The point was for you guys to tell me how you got it.
I'm obviously making like 1 mistake. There were like 5 questions identical to this one, just different numbers, that I got in less than 40 seconds. This one is just weird.

[Squeek]

Re: Help with an 'impossibly' easy math question

Same way I solve all math problems.

Guess and check.

[travman301]

Re: Help with an 'impossibly' easy math question

Uh, I just found numerators that came out to whole numbers. XD

[Zageron]

Re: Help with an 'impossibly' easy math question

BTW I'm not allowed to plug in numbers.
I have to do it by solving so it looks like x = 2y - 7 or something like that, then you have to plug that in to an equation and you get like y or something.

;_;

[travman301]

Re: Help with an 'impossibly' easy math question

Then you can add the two equations together, and then find the zeros to solve it.

But, thats like 50 times more work for such an easy problem.

[Zageron]

Re: Help with an 'impossibly' easy math question

Then you can add the two equations together, and then find the zeros to solve it.

But, thats like 50 times more work for such an easy problem.

Yeah. I dunno why there is so much work involved, I think it's so we know how to do insane questions in the future.

[travman301]

Re: Help with an 'impossibly' easy math question

You need to know how to do substitution and combination and stuff when you solve matrices and things like that. I think that's what your teacher is starting to get you ready for.

As for these though, just do the math in your head to get the answer. It's not worth the effort.

[dag12]

Re: Help with an 'impossibly' easy math question

Alright

-x - 2----y + 1
------ + ------ = 2 .... [1]
--3---------5


x + 2----y + 5
------ - ------ = -2 ... [2]
--7--------3

[1] * 15:
5(x - 2) + 3(y + 1) = 30

[2] * 21:
3(x + 2) - 7(y + 5) = -42

Simplify the system:
5x + 3y = 37 ... [1']
3x - 7y = -13 ... [2']

[1'] * 3:
15x + 9y = 111 ... [1'']

[2'] * 5:
15x - 35y = -65 ... [2'']

[1''] - [2'']:
44y = 176

Simplify:
y = 4

Substitute y = 4 into [1'] (Any of the previous equations work, but I just chose [1']):
5x + 3*4 = 37

Simplify:
5x = 25
x=5

Solution:
[ x = 5, y = 4]

[x After Dawn x]

Re: Help with an 'impossibly' easy math question

I just did it in my head and got the same answer as trav.

[Zageron]

Re: Help with an 'impossibly' easy math question

thank you dag12, now I can see what I got wrong.

Somehow 5(x - 2) ended up being 5x + 10
-_-;

In math if there is ever a - 2x or - 2, I always seem to get it mixed with positive.

[Jokee]

Re: Help with an 'impossibly' easy math question

-x - 2----y + 1
------ + ------ = 2
--3---------5

You have to transform the denominator into 1. so you take the whole equation and multiply by 15 (3x5) and you get -5x-10+3y+3=30

Then you isolate the y variable -> 3y=5x+37 -> y=(5x/3)+(37/3)

Then you do the same with the second equation and you get a similar answer. Then you compare the you 2 new equations and you'll get your answer.


Edit: Sorry I just saw that someone answered already :P