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March 4th, 2012, 08:31 PM   #1
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Add and Subtract Indicated

Okay, I know that I'm suppose to multiply the top and bottom so that the denominator is alike, but it's not. Ugh, I broke the bottom down to be in the first column and this is where I'm lost, the "r" . . . I've tried making both denominatiors 2r(r+6) by multiplying 2(r+6) just lost
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March 4th, 2012, 08:39 PM   #2
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Re: Add and Subtract Indicated

Quote:
Originally Posted by HellBunny
... I've tried making both denominators 2r(r+6) by multiplying [color=#000080]*** 1/r by ****[/color]2(r+6) just lost
That's good.
You'll also need to multiply the first term by r/r
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March 4th, 2012, 08:43 PM   #3
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Re: Add and Subtract Indicated

It's still not coming out the right answer,
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March 4th, 2012, 08:55 PM   #4
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Re: Add and Subtract Indicated

What's the "right answer"? I get:

3(r - 4)
---------
2r(r+6)

??
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March 4th, 2012, 08:57 PM   #5
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Re: Add and Subtract Indicated

That's the answer. But what do you have on the second denominator when you're multiplying?
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March 4th, 2012, 09:12 PM   #6
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Re: Add and Subtract Indicated

Not sure what you're asking, HB, but here's my steps:

5 / (2r + 12) - 1 / r

= [5r - 1(2r + 12)] / [r(2r + 12)]

= (5r - 2r - 12) / (2r^2 + 12r)

= (3r - 12) / [2r(r + 6)]

= [3(r - 4)] / [2r(r + 6)]

Like:
a/b - c/d
= (ad - bc) / bd

Hope that helps instead of confuses

Being 7/10 bald-headed, I musy say I'm jealous of your Afro
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March 4th, 2012, 11:25 PM   #7
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Re: Add and Subtract Indicated

Thanks, I'll give you some hair.
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