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Mathematics 22 Online
OpenStudy (anonymous):

plz help

OpenStudy (anonymous):

hi

OpenStudy (anonymous):

whats the question

OpenStudy (anonymous):

\[(3x)^-1 \over 4\]

OpenStudy (anonymous):

write each expression so that it contains only positive exponents

OpenStudy (anonymous):

I dunno this 1 im so sorry

OpenStudy (anonymous):

\[\frac{(3x)^{-1}}{ 4}=\frac{1}{4(3x)}\]

OpenStudy (anonymous):

how did you do that

OpenStudy (anonymous):

\(b^{-1}=\frac{1}{b}\)

OpenStudy (anonymous):

in general, \[b^{-n}=\frac{1}{b^n}\]

OpenStudy (anonymous):

how did you get b

OpenStudy (anonymous):

i picked \(b\) as a variable you can use anyone you prefer

OpenStudy (anonymous):

oh ok

OpenStudy (anonymous):

satellite are you there:(

OpenStudy (anonymous):

I don't know what else there is to say. What don't you understand?

OpenStudy (anonymous):

idk i just dont know how to do it

OpenStudy (anonymous):

what happened to the -1

OpenStudy (anonymous):

This is what your problem looks like, right? \[\frac{ (3x)^{-1} }{ 4 }\]

OpenStudy (anonymous):

This is what your problem looks like, right? \[\frac{ (3x)^{-1} }{ 4 }\]

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

Did you know that \[x^{-1}=\frac{ 1 }{ x }\]?

OpenStudy (anonymous):

no

OpenStudy (anonymous):

i thought x-1=1/x1

OpenStudy (anonymous):

Same thing. \[x^1=x\] just like \[3^{1}=3\]

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

but isnt negative 1

OpenStudy (anonymous):

One thing first. Whenever you want to say that x has an exponential value of -1, you should type x^-1 or x to the power of -1 rather than x-1 because x-1 is just subtraction.

OpenStudy (anonymous):

oh ok sorry

OpenStudy (anonymous):

Is this what you're saying?\[x^{-1}=\frac{ 1 }{ x^{1} }\]

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

Then you are right. But, as I said, \[x^{1}=x\] So you can just change the \[x^{1}\] to \[x\]

OpenStudy (anonymous):

oh ok

OpenStudy (anonymous):

This means that \[x^{−1}=\frac{ 1 }{ x }\]

OpenStudy (anonymous):

yeah i know

OpenStudy (anonymous):

Rewrite this so that there are only positive exponents:\[\frac{ 1 }{ x^{-1} }\]

OpenStudy (anonymous):

uh \[1\over x\]

OpenStudy (anonymous):

i think

OpenStudy (anonymous):

am i right

OpenStudy (anonymous):

No. General rule of thumb. If you see a negative number as an exponent, flip the term(with the exponent) over the fraction bar and make the exponent positive

OpenStudy (anonymous):

?

OpenStudy (anonymous):

so I flip x^-1 over to the numerator and get \[x^{-1}\] then I take away the negative sign which gets me \[x^{1}\] or \[x\]

OpenStudy (anonymous):

so every time there an equation like this \[1 \over x ^-1\] you have to flip

OpenStudy (anonymous):

Yes. But ONLY if the exponent is negative. Next problem:\[\frac{ 1 }{ x^{-2} }\]

OpenStudy (anonymous):

so I fliped x^21 over to the numerator and get x−2 then I take away the negative sign which gets me x2

OpenStudy (anonymous):

-2

OpenStudy (anonymous):

x^2 is right. Next one:\[x ^{-3}\]

OpenStudy (anonymous):

\[1\over x^2\]

OpenStudy (anonymous):

Are you sure?

OpenStudy (anonymous):

I think it's a silly mistake, but it was x^3, not x^2

OpenStudy (anonymous):

Might be because the number was so small.

OpenStudy (anonymous):

oh yeah it was a little as i looked closer it was a 3

OpenStudy (anonymous):

\[1 \over x^3\]

OpenStudy (anonymous):

Next one(and the important one to help you with your problem):\[\frac{ 4 }{ x^{-2} }\]

OpenStudy (anonymous):

idk 4/x^2

OpenStudy (anonymous):

Why don't you bring x^-2 to the numerator and take away the negative sign?

OpenStudy (anonymous):

so it would be 4x^2

OpenStudy (anonymous):

Exactly. Now can you do this?\[\frac{ (3x)^{-1} }{ 4 }\]

OpenStudy (anonymous):

If you really don't understand, no is a good answer too.

OpenStudy (anonymous):

im still thinking

OpenStudy (anonymous):

3x/4

OpenStudy (anonymous):

i got it wrong

OpenStudy (anonymous):

Then change it :P

OpenStudy (anonymous):

change what

OpenStudy (anonymous):

remember what we did with \[x^{-2}\]

OpenStudy (anonymous):

1/x^2

OpenStudy (anonymous):

We flipped it into the denominator and took away the negative sign to get \[\frac{ 1 }{ x^{2} }\]

OpenStudy (anonymous):

Can you apply this to your problem or should I just explain?

OpenStudy (anonymous):

but 3 is a numerator too it can turn to 1

OpenStudy (anonymous):

yeah you should explain i get everything you taught me i just can put it all together

OpenStudy (anonymous):

Do you agree that \[(3x)^{-1}=\frac{ 1 }{ (3x)^{1} }\]or \[\frac{ 1 }{ (3x) }\]

OpenStudy (anonymous):

\[1\over (3x)^1\]

OpenStudy (anonymous):

Errr I mean that it equals both but the lower one without the exponent of 1 is simplified

OpenStudy (anonymous):

But you agree with it, right?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

i should've looked at it as a whole

OpenStudy (anonymous):

Now do you agree that \[(3x)^{−1}\times \frac{ 1 }{ 4 }=\frac{ (3x)^{−1} }{ 4 }\]

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

so if you substitute the (3x)^-1 with \[\frac{ 1 }{ 3x}\] in the expression, you get \[\frac{ 1 }{ 4(3x) }\]

OpenStudy (anonymous):

and that simplifies to\[\frac{ 1 }{ 12x }\]

OpenStudy (anonymous):

But if you think about it, all I actually did was flip the (3x)^-1 over to the denominator and take away the negative sign|dw:1363833108473:dw|

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