View Full Version : solve 2x+5y=-2,y=-x/2; b=2/3a,8a-3b=3: fractions confuse me

kaymarie

10-25-2008, 03:24 PM

I'm stuck on this problem:

2x+5y=-2

y=-x/2

the -x/2 is throwing me off, i'm not sure how to get rid of it.

And then there's this problem:

b=2/3a

8a-3b=3

the fraction is confusing me, i'm not sure how to get started on it.

Thanks so much!

Loren

10-25-2008, 03:50 PM

2x+5y=-2

y=-x/2

Replace the y in the first equation with -x/2 from the second equation getting...

2x+5(\frac{-x}{2})=-2

and go from there.

Denis

10-25-2008, 05:11 PM

b=2/3a

the fraction is confusing me, i'm not sure how to get started on it.

Rule: if a = b/c, then ac = b : known as crisscross multiplication

That's all there is to that...kapish?

Similarly (so you know), if a/b = c/d, then ad = bc

TRY it:

2 / 4 = 5 / 10 (both 1/2)

2 * 10 = 4 * 5 ....clear??

mmm4444bot

10-25-2008, 05:13 PM

... And then there's this problem:

b=(2/3)a grouping symbols added for clarity

the fraction is confusing me ...

If you multiply both sides of the above equation by 3, then the fraction will be gone.

kaymarie

10-25-2008, 06:39 PM

2x+5y=-2

y=-x/2

Replace the y in the first equation with -x/2 from the second equation getting...

2x+5(\frac{-x}{2})=-2

and go from there.

But i still have that fraction in there, do i multiply like 5/1 times -x/2?

Mrspi

10-25-2008, 09:20 PM

Replace the y in the first equation with -x/2 from the second equation getting...

2x+5(\frac{-x}{2})=-2 and go from there.

But i still have that fraction in there, do i multiply like 5/1 times -x/2?

Did you READ the previous responses? I'm guessing you didn't, or you would not be asking the SAME question again.

I am thinking that you would LIKE multiply both sides of your original equation by 2, since that is the denominator of the fraction in the equation....

2* 2x + 2*5(-x/2) = 2(-2)

4x + (-5x) = -4

NOW can you take it from here?

kaymarie

10-26-2008, 11:06 PM

Did you READ the previous responses? I'm guessing you didn't, or you would not be asking the SAME question again.

I am thinking that you would LIKE multiply both sides of your original equation by 2, since that is the denominator of the fraction in the equation....

2* 2x + 2*5(-x/2) = 2(-2)

4x + (-5x) = -4

NOW can you take it from here?

That was a very rude response, it was an honest question, i wasnt trying to sound like a dumbass. Thanks for you're lovely attitude with that.

mmm4444bot

10-26-2008, 11:51 PM

Kay Marie:

Denis told you how to clear an equation of fractions.

I told you how to clear an equation of fractions.

Why are you asking yet again about how to clear an equation of fractions?

I hold students to a high standard here. You need to think more.

Do you know how to do arithmetic with fractions? You could simply subtract 5/2 from 2.

2x - \frac{5}{2}x = -2

-\frac{1}{2}x = -2

stapel

10-27-2008, 11:04 AM

That was a very rude response, it was an honest question...

If you'd like to engage "honestly" in this process, then, by all means, please show some evidence of at least having read the replies.

If you truly are a helpless child who knows nothing of fractions, and thus are unable to understand the help that has repeatedly been provided, then you need to ask your mommy to hire a tutor or contract with your local Kumon Tutoring Centre, or some similar service, so you can be taught the months or years of missing material.

If, on the other hand, you are grown and in high school or above, then you need to take some responsibility for your learning process. A good start would be to read the replies you've received, rather than merely expressing angry neediness and asking the same question over and over.

My best wishes to you.

Eliz.

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