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1. Simultaneous equations with fractions?
Hello

Quick problem that I havent studied before and cant seem to make anything of it from the internet, so here it is...

x/2 + y/3 = 5
x/3 + y/4 = 1

I've tried multiplying them out and substituting it back in, but as said I just cant seem to do it..

The official answer is y=84 and x=66...helpful step by step would be greatly appreciated!
2. Re: Simultaneous equations with fractions?
Multiply the first equation by 24

Multiply the second equation by 36
3. Re: Simultaneous equations with fractions?
Show your working out on here. Can tell you where the mistakes are
4. Re: Simultaneous equations with fractions?
(Original post by 24hoursmiles)
Hello

Quick problem that I havent studied before and cant seem to make anything of it from the internet, so here it is...

x/2 + y/3 = 5
x/3 + y/4 = 1

I've tried multiplying them out and substituting it back in, but as said I just cant seem to do it..

The official answer is y=84 and x=66...helpful step by step would be greatly appreciated!
multiply the fractions so it becomes just a simple equation

x/2 + y/3 = 5
x(3)+y(2)=5(2)(3) becomes 3x+2y=30
then the second one...
x/3 + y/4 = 1
x(4)+y(3)=1(4)(3) becomes 4x+3y=12

then solve the simultaneous equation
3x+2y=30 (*by 3)
4x+3y=12 (*by 2)

when multiplied makes
9x+6y=90
8x+6y=24
then solve using elimination method and you're done!
9x+6y=90
8x+6y=24 (minus them from one another)

x=66 then factor that into the equation
3x+2y=30 (using the simpler first equation for ease)
3(66)+2y=30
198+2y=30 (-198 from both sides)
2y=-168 (divide both sides by 2)
y=-84

and there you go x=66 and y=-84

why has someone negged the correct answer??
Last edited by pseudonymegg; 25-07-2012 at 20:56.
5. Re: Simultaneous equations with fractions?
(Original post by 24hoursmiles)
Hello

Quick problem that I havent studied before and cant seem to make anything of it from the internet, so here it is...

x/2 + y/3 = 5
x/3 + y/4 = 1

I've tried multiplying them out and substituting it back in, but as said I just cant seem to do it..

The official answer is y=84 and x=66...helpful step by step would be greatly appreciated!
My math skills have degraded by a bit but you sure y isnt minus?
6. Re: Simultaneous equations with fractions?
Yeah y is -84 ?
7. Re: Simultaneous equations with fractions?
(Original post by jordanosborn)
Yeah y is -84 ?
yeah i got that :L dunno if OP used his answers or ones from a book??
Last edited by pseudonymegg; 24-07-2012 at 19:47.
8. Re: Simultaneous equations with fractions?
Put it in a matrix and then use row elimination
9. Re: Simultaneous equations with fractions?
(Original post by Dmon1Unlimited)
My math skills have degraded by a bit but you sure y isnt minus?
whhoops so sorry just did the final equation yep 'tis a minus x = 66 and y= -84
10. Re: Simultaneous equations with fractions?
(Original post by pseudonymegg)
no, there is no minus at all the answers are correct. Follow my method and you then solve a very simple simultaneous equation to get the answers given by OP
But of course that there is a minus! You must have made some sort of mistake. It's exactly:

edit: crossed with @up
11. Re: Simultaneous equations with fractions?
(Original post by martinix)
Wouldn't it be better to multiply the 1st equation by 6 and the second by 12, just as pseudonymeg cleverly did?
erm she multiplied by 18 and 24
12. Re: Simultaneous equations with fractions?
(Original post by pseudonymegg)
and there you go x=66 and y=-84
Thank-you so much for going through it. I now understand where i went wrong, for some reason, it escaped me to multiply the 5. Thanks again, much appreciated!

(Original post by Dmon1Unlimited)
My math skills have degraded by a bit but you sure y isnt minus?
Yes, sorrryy, I missed it out on my post!
13. Re: Simultaneous equations with fractions?
(Original post by 24hoursmiles)
Thank-you so much for going through it. I now understand where i went wrong, for some reason, it escaped me to multiply the 5. Thanks again, much appreciated!
yeah you're welcome glad to help
14. Re: Simultaneous equations with fractions?
(Original post by TenOfThem)
erm she multiplied by 18 and 24
depends to what point of her solvind procedure you are referring to... At the beginning she evidently did multiply by 6 and 12...

Anyway, nvm, it's not that important, is it?