# What is Fractional exponents: Definition and 19 Discussions

In probability theory, fractional Brownian motion (fBm), also called a fractal Brownian motion, is a generalization of Brownian motion. Unlike classical Brownian motion, the increments of fBm need not be independent. fBm is a continuous-time Gaussian process BH(t) on [0, T], that starts at zero, has expectation zero for all t in [0, T], and has the following covariance function:

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{\displaystyle E[B_{H}(t)B_{H}(s)]={\tfrac {1}{2}}(|t|^{2H}+|s|^{2H}-|t-s|^{2H}),}
where H is a real number in (0, 1), called the Hurst index or Hurst parameter associated with the fractional Brownian motion. The Hurst exponent describes the raggedness of the resultant motion, with a higher value leading to a smoother motion. It was introduced by Mandelbrot & van Ness (1968).
The value of H determines what kind of process the fBm is:

if H = 1/2 then the process is in fact a Brownian motion or Wiener process;
if H > 1/2 then the increments of the process are positively correlated;
if H < 1/2 then the increments of the process are negatively correlated.The increment process, X(t) = BH(t+1) − BH(t), is known as fractional Gaussian noise.
There is also a generalization of fractional Brownian motion: n-th order fractional Brownian motion, abbreviated as n-fBm. n-fBm is a Gaussian, self-similar, non-stationary process whose increments of order n are stationary. For n = 1, n-fBm is classical fBm.
Like the Brownian motion that it generalizes, fractional Brownian motion is named after 19th century biologist Robert Brown; fractional Gaussian noise is named after mathematician Carl Friedrich Gauss.

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1. ### Powers with fractional exponents that have an even denominator

(If I should have posted this in the Math thread instead of the Homework thread, please let me know.) I have three questions which I will ask in sequence. They all relate to each other. I've typed my questions and solutions attempts below. I've also attached a hand-written version of this...
2. ### Why do fractional exponents result in the square root operator?

So I got the answer through a little addition i.e 9^(1/2) multiplied by 9^(1/2) = 9^1 or 9 3 x 3 = 9 so 3 is the answer to what is 9^(1/2) I've tested this out with a few other numbers and have made this generalization, x^(1/2) = √x It seems to make the equations orderly and consistent but is...
3. E

### B Resolving index laws for fractional exponents

I was just thinking about this earlier and couldn't come up with a good enough resolution. I'm guessing it's a matter of convention more than anything. If we have ##x^{2} = a##, taking the principle root of both sides gives ##\sqrt{x^{2}} = \sqrt{a} \implies |x| = \sqrt{a}##. Yet evidently if...
4. ### Intuitive explanation of fractional exponents?

Homework Statement What would have caused humans to come up with fractional exponent notations? Homework EquationsThe Attempt at a Solution I understand that it makes sense to use the exponent notation when we have to multiply the same number a number of times. For example, 10^8 is the short...
5. ### Multiplying Algebraic Fractional Exponents

Homework Statement a3/2a5/4 Homework EquationsThe Attempt at a Solution I'm hoping you can help. My solution to this problem would be: a3/2+5/4=a8/6=a4/3 But the answer in the back of my book is given as a11/4 I'm confused!
6. ### Pulling fractional exponents out of an expression

Homework Statement Find critical numbers of the function: F(x)=t^3/4 - 2t^1/4 Derivative I got: F'(x)=3/4 t^-1/4 - 1/2 t^-3/4 Homework EquationsThe Attempt at a Solution I have found the derivative and I understand I must pull out a t in order to find critical numbers, and run across this...
7. ### Binomial expansion for fractional power

Homework Statement So, I'm solving a dipole thing and I have these vectors: |r + d - r'| = (r² + d² - r'²)(1/2) Homework Equations I want to expand this but I have no idea how! I know I may have an infinite power series, but I may expand at the square terms tops... Before I needed to do the...
8. ### Doing Fractional Exponents on Basic Scientific Calculator

Suppose you have 8-1/3 and want a precise value for it. How would you go about calculating this on a regular scientific calculator. I punched in: 8, then the exponent button, then 1, then negative, then division, and finally 3. The calculator reads "error."
9. ### How far apart are two point charges....

1. How far apart must two point charges of 75.0 nC be to have a force of 1.00 N between them?Homework Equations F = k Q1Q2/r2[/B]3. 1N = 9e10 * 75e-10 squared/r squared r2= 9e10 * 75e-10 squared/1N r2= 9*75*75e-10 r2= 5.0625e-7 r= square root of 5.0625 * square...
10. ### Challenge 23: Fractional exponents

With only only paper & pencil (no calculator or logarithmic tables), figure out which of the following expressions has a greater value: 101/10 or 31/3. Please make use of the spoiler tag and write out your full explanation, not just the answer.
11. ### Fractional Exponents (How is it done?)

How does 2^5/2 become 2^2 multiplied by 2^1/2? (The '^' means 'to the power of' so 2 to the power of 5/2. I am not sure how to write this as an exponent as this is my first post.) 2^5/2 = 2^2 × 2^1/2 So 2^2 = 4 and 2^1/2 means Square Root so there is a radical sign, so it becomes √2. I...
12. ### Add, sub, multiply, and dividing w/ fractional exponents & radicals

Okay so I'm in Calculus 1 and we are working on derivatives. I understand it all but I have been having some trouble with some basic math skills that I cannot remember from high school and I can't seem to find a good tutorial anywhere online. I am having problems with multiplying fractional...
13. ### Solving nonlinear first order DE w/ fractional exponents

Hello. I have simple DE y' + p y^(1/2) = q --------------- y'=dy/dt p,q=constant I am confused because I tried bernoulli's method to solve and I think I exploded the universe. Basically, my initial condition of t=0,y=0 made infinity, not right. I'm not sure that method works when there...
14. ### Solve Fractional Exponents: Logic Explained

Can someone explain the logic behind this? For instance if 2 to the 3rd power = 2 x 2 x 2 =8 So 2 to the 3rd power is telling me I have 2 multiplied by itself 3 times. Now how would I solve for 2 to the 1/3rd power? It is telling me I have 2 multiplied by itself 1/3 times but how do you...
15. ### Solving Equations with Fractional Exponents

The question is x2/3 - x1/3 - 2 = 0 So the first thing I did was: x2/3 - x1/3 = 2 Then, I put both sides to the power of three, so I got: x2 - x1 = 8 From there I factorized: x (x - 1) =8 And got the answers: x = 8 or x = 9, the book however, says the correct answers are -1 and 8. Any...
16. ### Fractional exponents of negative

I've been toying around with stuff I probably shouldn't be. :biggrin: I've been sketching a graph of y=x^n where n is a rational number (as opposed to an integer). Of course, when I get into the fractional exponents, the negative portion of the curve ends up being imaginary (eg. x=-2,n=2.5...
17. ### Factoring Algebraic Expressions with Fractional Exponents

Homework Statement (4x-1)^{1/2}-1/3(4x-1)^{3/2}Homework Equations The Attempt at a Solution I think the GCF is (4x-1)^{1/2}. So, I get (4x-1)^{1/2}(1+(-1/3(4x-1))) = (4x-1)^{1/2}(-4/3x+4/3) = -4/3(4x-1)^{1/2}(x-1) However, the answer in the book is 4/3(4x-1)^{1/2}(x-1). I've done it several...
18. ### Binomial theorem for fractional exponents?

I am curious, is there any way to use the binomial theorem for fractional exponents? Is there any other way to expand a binomial with a fractional exponent? I suppose Newton's theorem is not a way since it requires factorials. Thanks!
19. ### Fractional exponents of negative numbers?

I was just playing around in my head. I wanted to plot this graph: y=x^2.5; x=-2 This is valid right? My calc says it's invalid input.