Math 20 linear Equations by elimination

**t-dot** · September 29th 2009, 10:19 AM

I can't seem to get the correct answer on this one.
Solve by elimination:
x+2/6 - 3(y+2)/2 = 1
x-2/2 + y-1/3 =0
(sorry i don't know how to make fractions in html...)

the answer is supposed to be (4,-2)
i think i'm messing up when i try to get rid of the fractions.
i get:
x+9y=17 and 3x+2y=8
i times the first one by -3 so i can cancel the x when added together and end up with 29y=65 which doesn't work.

any takers?

**t-dot** · September 29th 2009, 10:36 AM

i'm having the same problem with the decimals. i have no idea how to approach this.

0.3x-o.5=1.2
0.7x-0.2y=-0.1
solve by elimination yet again.

do i change everything to fractions?
i'm really not sure how to do this one....

**artvandalay11** · September 29th 2009, 10:36 AM

Originally Posted by t-dot

I can't seem to get the correct answer on this one.
Solve by elimination:
x+2/6 - 3(y+2)/2 = 1
x-2/2 + y-1/3 =0
(sorry i don't know how to make fractions in html...)

the answer is supposed to be (4,-2)
i think i'm messing up when i try to get rid of the fractions.
i get:
x+9y=17 and 3x+2y=8
i times the first one by -3 so i can cancel the x when added together and end up with 29y=65 which doesn't work.

any takers?

I am going to assume that the two equations you need solved are $\frac{x+2}{6}-\frac{3(y+2)}{2}=1$ and $\frac{x-2}{2}+\frac{y-1}{3}=0$

I said assume because without parenthesis what you wrote implies $x+\frac{2}{6}-\frac{3(y+2)}{2}=1$ and $x-\frac{2}{2}+y-\frac{1}{3}=0$ I understand that you do not know latex and cannot write fractions, but you must be careful with order of operations and use ( ) to denote what goes with what

Anyway...

$\frac{x+2}{6}-\frac{3(y+2)}{2}=1$ and $\frac{x-2}{2}+\frac{y-1}{3}=0$

Let's multiply both sides of both equations by 6, this will cancel the denominators and we'll get

$x+2-3(3(y+2))=6$ and $3(x-2)+2(y-1)=0$

So $x+2-9y-18=6$ and $3x-6+2y-2=0$

So $x-9y=6-2+18=22$ and $3x+2y=8$

Can you solve $x-9y=22$ and $3x+2y=8$ ?

**artvandalay11** · September 29th 2009, 10:38 AM

Originally Posted by t-dot

i'm having the same problem with the decimals. i have no idea how to approach this.

0.3x-o.5=1.2
0.7x-0.2y=-0.1
solve by elimination yet again.

do i change everything to fractions?
i'm really not sure how to do this one....

No you do not need to change everything to fractions, all of these change to numbers very easily if we multiply both sides of both equations by 10, then we get

3x-5=12 and 7x-2y=-1

**t-dot** · September 29th 2009, 10:58 AM

thanks so much i was able to get rid of everything after that

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Math 20 linear Equations by elimination

decimals as well.

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