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

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!

Re: Substitution

2x+5y=-2
y=-x/2

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

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

and go from there.

Re: Substitution

kaymarie said:

b=2/3a
the fraction is confusing me, i'm not sure how to get started on it.

Click to expand...

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??

Re: Substitution

kaymarie said:

... And then there's this problem:

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

the fraction is confusing me ...

Click to expand...

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

Re: Substitution

Loren said:

2x+5y=-2
y=-x/2

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

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

and go from there.

Click to expand...

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

Re: Substitution

Loren said:

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

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

Click to expand...

kaymarie said:

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

Click to expand...

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?

Re: Substitution

Mrspi said:

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?

Click to expand...

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.

Re: Substitution

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.

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

\(\displaystyle -\frac{1}{2}x = -2\)

kaymarie said:

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

Click to expand...

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.