# Recent content by Mandlebra

1. ### When the Rational Root Theorem Fails

The quartic formula! Didn't you learn it in school? :p
2. ### Oscillation in Dynamic Models

There are many cycles with oscillatory convergence, with the limit actually a limit cycle. The hailstone sequences come g to mind. @chiro
3. ### Oscillation in Dynamic Models

Oscillations in this case are more often called orbits
4. ### What exactly allows a differential relation form of an equation?

For f not a function of y or theta, dy= fdθ Then its just symbol pushing.
5. ### Professional Help Needed-Elementary Number Theory

Is it really ALL? That makes this far more interesting. Mind linking a paper or something?
6. ### Zeros of f(x) vs. Zeros of f'(x)

If f is a polynomial with all roots of multiplicity one, then the derivative does not have a zero in common with f. To see this, express f factored, use product rule for derivatives.
7. ### An identity of Ramanujan's

I'm pretty sure it is infinite. Good luck, ram was a beast
8. ### Indefinite Integration of function's like log(cos(x))?

I think this guy gets the u= x-pi/2 treatment. symmetry :)
9. ### Principal curvature used in a contact problem

Curvature is the reciprocal of the radius. Is that what is confusing you?

If the sum is divisibleby abc what does that say about the terms
11. ### If F is ANY field then (x^m-1)|(x^n-1) in F[x] if and only if m|n.

Ok aassuming they are: Perform division, paying attention to the form of the powers you get for the quotient
12. ### If F is ANY field then (x^m-1)|(x^n-1) in F[x] if and only if m|n.

What are m,n? Naturals I assume
13. ### Lim x to 0 x*sin(1/x)

I thought it was easily inferred...
14. ### Prime numbers : a math question for the pro

A lot of modern analytic number theory advances are being made using hardy's major and minor circle (arc?) Technique, but most advances just seem to be bounds improvements
15. ### Hi, I m trying to find out, what is imaginary unit/number. i^2

On the quaternion bit, any purely imaginary unit quaternion is a root of -1. Also they are 4D not 3 : p