What is the Limit of e^(1/x) as x Approaches 0 and the Direction Matters?

In summary, the conversation discusses a solution that involves taking the limit as b approaches 0 from below. The person writing the solution made a small mistake, but the answer is still correct. It is important to consider the direction from which 0 is approached, as approaching from the right results in the function blowing up.
  • #1
Phys12
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1cbf4ac287084491ad5b7ed95f9ed522.jpg

In this solution, in the last 3rd line, I get the first part (-e^-1 - e^-1), however, after the '-' symbol, the person writes (1/b * e^1/b - e^1/b) and takes the limit as b->0. However, shouldn't this give him (inf. * e^inf - e^inf)?

Thanks
(His answer is correct, by the way)
 
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  • #2
Phys12 said:
1cbf4ac287084491ad5b7ed95f9ed522.jpg

In this solution, in the last 3rd line, I get the first part (-e^-1 - e^-1), however, after the '-' symbol, the person writes (1/b * e^1/b - e^1/b) and takes the limit as b->0. However, shouldn't this give him (inf. * e^inf - e^inf)?

Thanks
(His answer is correct, by the way)
b approaches 0 from below, so 1/b tends to minus infinity. There is a small mistake: the 1 in the (1 . 0 - 0) term. Need to use the fact that x e-x tends to 0 as x tends to +infinity.
 
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  • #3
haruspex said:
b approaches 0 from below, so 1/b tends to minus infinity. There is a small mistake: the 1 in the (1 . 0 - 0) term. Need to use the fact that x e-x tends to 0 as x tends to +infinity.
Ohk! I didn't notice the fact that we were approaching 0 from the left hand side. Thanks! :)
 
  • #4
Phys12 said:
Ohk! I didn't notice the fact that we were approaching 0 from the left hand side. Thanks! :)

Right: if you approach 0 from the right the function blows up: ##\lim_{x \to 0+} e^{1/x} = +\infty##.
 

Related to What is the Limit of e^(1/x) as x Approaches 0 and the Direction Matters?

1. What is the limit of e^(1/x) as x approaches 0?

The limit of e^(1/x) as x approaches 0 is equal to infinity. This can be seen by taking the limit of the function as x approaches 0 from both the positive and negative sides, which will result in a very large positive value.

2. How can we prove that the limit of e^(1/x) as x approaches 0 is infinity?

We can prove this by using the definition of a limit, which states that for a function f(x), the limit as x approaches a is equal to L if for any positive number ε, there exists a positive number δ such that if 0 < |x-a| < δ, then |f(x) - L| < ε. In the case of e^(1/x) as x approaches 0, we can choose a value for δ that will result in a very large value for f(x), thus showing that the limit is infinity.

3. Can the limit of e^(1/x) as x approaches 0 be negative infinity?

No, the limit of e^(1/x) as x approaches 0 can only be positive infinity. This is because as x approaches 0 from the positive side, e^(1/x) will approach infinity, and as x approaches 0 from the negative side, e^(1/x) will approach 0. Since infinity is not a finite number, it cannot have a negative counterpart.

4. Is it possible for the limit of e^(1/x) as x approaches 0 to not exist?

Yes, it is possible for the limit of e^(1/x) as x approaches 0 to not exist. This can happen if the function oscillates or if the limit approaches different values from the positive and negative sides.

5. How does the graph of e^(1/x) as x approaches 0 look like?

The graph of e^(1/x) as x approaches 0 is a vertical asymptote at x=0. As x gets closer and closer to 0, the graph will get steeper and steeper, approaching infinity on the positive side and 0 on the negative side.

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