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Topic: Please help me simplify this expression.
Replies: 5   Last Post: Jan 24, 2005 2:20 AM

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Rob Morewood

Posts: 171
Registered: 12/6/04
Re: Please help me simplify this expression.
Posted: Jan 24, 2005 2:20 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply wrote:
: Problem: [x(x+2)^-(1/2) + (x+2)^(1/2) ] / (x+2)^(3/2)
: I first separate out the problem and combine the lower exponents to get
: [x((2/(x+2)) + 1/(x+2)] / (x+2)

I'm not sure what you mean by that, but the result is clearly incorrect.
Put x=2 (so that the square roots are easy) into the original expression
and get 3/8. In your expression, x=2 gives 5/16.

You want to change the denominator from (x+2)^(3/2) to just (x+2).
A standard trick for simplifing fractions is to multiply or divide
the numerator and denominator by the same amount. Try (x+2)^-(1/2).
That will give you the denominator you desire, but a simplier
numerator than you have above.

Perhaps a better approach would be to multiply the numerator and
denominator by (x+2)^(1/2). That still eliminates the fractional
exponents AND also eliminates the negative exponents at the same

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