Which increases faster e^x or x^e ?

  • Thread starter Roni1985
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In summary, the exponential growth of e^x increases faster than the exponential growth of x^e. This can be proven by comparing the derivatives of both equations and taking the limit as x approaches infinity. The limit of the ratio of the two equations shows that e^x grows faster than ex^(e-1).
  • #1
Roni1985
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Homework Statement


which increases faster e^x or x^e ?

Homework Equations


The Attempt at a Solution



My attempt was taking the log of both, assuming it doesn't change anything (is this assumption correct?)

x*ln(e) ------------------------ e*ln(x)

now I took the derivative

1 ------------------------ e/x

and I said that if
0<x<e, x^e increases faster
otherwise, e^x is faster

Is my logic correct?

Thanks
 
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  • #2
No, you can't just take the log of both. You aren't dealing with an equality you are comparing two equations. For specific values, your procedure of deriving both and comparing when one is greater works fine, but you have to derive the original equations.

In general though, exponential growth (blank^x) grows faster than x^blank (whatever that is called), and you can prove that with limits.
 
  • #3
Vorde said:
No, you can't just take the log of both. You aren't dealing with an equality you are comparing two equations. For specific values, your procedure of deriving both and comparing when one is greater works fine, but you have to derive the original equations.

In general though, exponential growth (blank^x) grows faster than x^blank (whatever that is called), and you can prove that with limits.

Thanks for the reply.

How can you prove it with limits?
lim x-> inf
and then lim x-> -inf
?
 
  • #4
Or simply consider derivatives:
d/dx (e^x) = e^x and d/dx(x^e)=ex^(e-1)
These tell you how fast each function is increasing at each x, hence you can work out which function is increasing faster at each x.
 
  • #5
Gengar said:
Or simply consider derivatives:
d/dx (e^x) = e^x and d/dx(x^e)=ex^(e-1)
These tell you how fast each function is increasing at each x, hence you can work out which function is increasing faster at each x.

But you are using the fact:

"exponential growth (blank^x) grows faster than x^blank (whatever that is called)"

I want to prove it.
how do you see that
e^x grows faster then ex^(e-1) ?
 
  • #6
You have to consider the limit of the ratio of the two equations as x-->inf. Using l'hopital's rule, you can see the difference in the rates of change.
 

Related to Which increases faster e^x or x^e ?

1. What is e^x and x^e?

e^x and x^e are both mathematical functions. e^x is the exponential function where e is a mathematical constant approximately equal to 2.71828 and x is the power or exponent. x^e is the power function where x is the base and e is the exponent.

2. Which function increases faster, e^x or x^e?

Generally, e^x increases faster than x^e. This is because the value of e is larger than the value of x, so when raised to a power, e will result in a larger number than x^e.

3. Is there any situation where x^e increases faster than e^x?

Yes, there can be situations where x^e increases faster than e^x. This can happen when x is a large number, as the difference between e^x and x^e decreases as x increases.

4. How can I determine which function increases faster without graphing?

You can determine which function increases faster by comparing the values of e^x and x^e for different values of x. If e^x is consistently larger than x^e, then e^x increases faster. If the values of x^e become larger than e^x at some point, then x^e increases faster.

5. Is there a way to mathematically prove which function increases faster?

Yes, there is a mathematical proof using calculus to show that e^x increases faster than x^e for all values of x. This can be done by comparing the derivatives of the two functions and showing that the derivative of e^x is always larger than the derivative of x^e.

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