moo5003 wrote:Hey, I was just reviewing all the tests for tmmrws GRE exam and I cant seem to find the correct answer for problem #63.
f(x) = xe^(-x^2 - x^-2) for x!= 0
and 0 for x=0
How many horizontal tangent lines are there for f(x)?
Answer: D (I guessed c)
I found f' and I can only seem to get two values for when the derivative is 0. Can anyone tell me where the third is?
EDIT: I'm guessing its because as x approaches 0 the derivative approaches 0. Missed this :/, should have expected something like that since it isnt defined at 0 (at least for the derivative).
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