Simple Systems of equations.

AIME15 · Subject: Simple Systems of equations. Wed Aug 13, 2008 2:41 pm

3x+y=10
y=9

What is x?

Plug y=9 into the first equation to get:

3x+9=10

Subtract 9 from both sides and divide by 3:

x=1/3

Dojo, you need to install LaTeX on these servers

Dojo · Subject: Re: Simple Systems of equations. Wed Aug 13, 2008 2:45 pm

yeah yeah yeah I know, but i cant
The web hoster Im using is going to install it soon, i hope Shocked

I'll try.

_________________
~Dojo

herefishyfishy1 · Subject: Re: Simple Systems of equations. Sun Aug 17, 2008 6:32 am

AIME15 wrote:

3x+y=10
y=9

What is x?

Plug y=9 into the first equation to get:

3x+9=10

Subtract 9 from both sides and divide by 3:

x=10/9.

Dojo, you need to install LaTeX on these servers

I'm sure you mean x=1/3.

AIME15 · Subject: Re: Simple Systems of equations. Sun Aug 17, 2008 12:31 pm

Thanks fishy. I swear i typed 1/3 the first time Very Happy

Dojo · Subject: Re: Simple Systems of equations. Tue Aug 19, 2008 10:22 pm

Hmm...
You should make more questions here you dont just give the y variable.

_________________
~Dojo

isabella2296 · Subject: Re: Simple Systems of equations. Wed Aug 20, 2008 7:38 am

Here's one:

John orders 15 books in total. Some are Math books and some are Fantasy books. Math books cost $30 dollars each and Fantasy books cost $12 each. The total price of the books is $306. How many Math books did he order?

herefishyfishy1 · Subject: Re: Simple Systems of equations. Wed Aug 20, 2008 8:00 am

Solving with systems of equations:

x+y=15
30x+12y=306

12x+12y=180
18x=126
x=7