stuck on this limit problem

Limits, differentiation, related rates, integration, trig integrals, etc.
PaulKraemer
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stuck on this limit problem

Postby PaulKraemer » Tue Apr 12, 2011 1:30 pm

Hi,

lim as h -> 0 of
( (2+h)^(-2) - (2)^(-2) ) / h

I can't figure out how to get started on this problem. I assume I have to eliminate h from the denominator, but I am totally stuck.

Any help or hints would be greatly appreciated.

Thanks in advance,
Paul

nona.m.nona
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Re: stuck on this limit problem

Postby nona.m.nona » Tue Apr 12, 2011 8:10 pm

PaulKraemer wrote:lim as h -> 0 of
( (2+h)^(-2) - (2)^(-2) ) / h

I can't figure out how to get started on this problem.

For the time being, ignore the "divided by h" part. In what remains:

Convert the negative exponents to positive by moving their bases appropriately.

Convert to the common denominator.

Square out the two expressions, and simplify the resulting numerator. Move the common factor out front.

Put the result "over h", and "cancel".


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