solve the solution

AshleyRae09 · #1 Sep 25, 2009, 07:31 PM

how do you solve for the solution
x+9y=2(1)
x=9-y(2)

ohsohappy · Sep 25, 2009, 07:34 PM

What level of math is this?

AshleyRae09 · Sep 25, 2009, 07:35 PM

its algebra in college

ohsohappy · Sep 25, 2009, 07:38 PM

Haa crap once sec, I'll ask my boyfriend. Tutors Calculus ane linear Algebra. So he's a smarty pants.

AshleyRae09 · Sep 25, 2009, 07:39 PM

thank you because im stuck on that one and another one i posted if you could look at that one for me? thanks

ohsohappy · Sep 25, 2009, 07:40 PM

Quote:

Originally Posted by AshleyRae09

thank you because im stuck on that one and another one i posted if you could look at that one for me? thanks

Maybe copy and paste it?

AshleyRae09 · Sep 25, 2009, 07:42 PM

solve with add and multiply 5+6x<53

ohsohappy · Sep 25, 2009, 07:45 PM

When's it due? monday? He might be taking his time. I had to text it to him.

AshleyRae09 · Sep 25, 2009, 07:54 PM

yeah its due monday
thankss

Unknown008 · Sep 26, 2009, 01:29 AM

Here, the easiest way to solve it is by substitution.

$x+9y=2$
$x=9-y$

The second equation shows you the 'value' of x. So, use that in the first equation.

$x+9y=2$

Since 'x' is 9-y, replace the value of 'x' like this:

$(9-y)+9y=2$

Did you see it? I replaced the x by its equal value, that is 9-y.

Now, it's easy to find y.

$(9-y)+9y=2$

$9-y+9y=2$

- y + 9y gives + 8y

$9+8y=2$

Now remove 9 from both sides:

$9+8y - 9=2 - 9$

The 9 cancels out on the left hand side:

$\cancel{9}+8y \cancel{- 9}=2 - 9$

$8y=-7$

Divide both sides by 8:

$\frac{8y}{8}=\frac{-7}{8}$

The 8 cancel out on the left hand side:

$\frac{\cancel{8}y}{\cancel{8}}=\frac{-7}{8}$

$y=-\frac{7}{8}$

Here is the value of y.

Now replace that value in the previous equation, $x=9-y$

$x=9-(-\frac78)$

$x=9+\frac78$

$x=\large{9}\frac78$



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