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Dec
5
answered Word Permutations
Dec
5
comment What am I doing wrong? (using the formula for lowering powers)
@Cherry_Developer Because $\cos(4x)$ is one object, and also $-\cos(4x) \neq cos(-4x)$
Dec
4
comment What am I doing wrong? (using the formula for lowering powers)
@Cherry_Developer Exactly
Dec
4
answered Find the radius of convergence, R, of the series. and Find the interval, I, of convergence of the series.
Dec
4
revised Find the radius of convergence, R, of the series. and Find the interval, I, of convergence of the series.
added 8 characters in body
Dec
4
answered What am I doing wrong? (using the formula for lowering powers)
Dec
4
comment Laplace transform involving two functions of t
Also, if you are integrating in $dr$, $f(t),g(t)$ go outside of the integral. If you are integrating in $dt$ , you need to set $r = -s$, not $r=s$ as you suggest
Dec
4
comment Laplace transform involving two functions of t
Depends what you want, wikipedia lists a pretty nasty identity for what you tried to do (en.wikipedia.org/wiki/Laplace_transform)
Dec
4
revised Laplace transform involving two functions of t
edited title
Dec
4
comment Laplace transform involving two functions of t
What are $f$ and $g$? What is the integral with respect to, $dt$ or $dr$???
Dec
2
comment In a limit proof, what are the assumptions?
@Amad27 Generally, to prove such things, you fix some arbitrary $\epsilon > 0$ and find the value of $\delta_2$, such that for any $x \in (a-\delta_2,a+\delta_2)$ you will have the desired inequality $||f(x)|-|L|| < \epsilon$.
Dec
2
revised How do I find the limits of integration?
added 54 characters in body
Dec
2
answered In a limit proof, what are the assumptions?
Dec
2
comment Calculation of all positive integer $x$ for which $\displaystyle \lfloor \log_{2}(x) \rfloor = \lfloor \log_{3}(x) \rfloor \;,$
you likely want $\ln x$ in the last inequality?
Dec
2
comment Innovation behind formula for surface area and volume of a sphere
@Half-Bloodprince here is the original Euclid's proof of that fact: aleph0.clarku.edu/~djoyce/java/elements/bookXII/propXII10.html
Dec
2
comment Innovation behind formula for surface area and volume of a sphere
@Half-Bloodprince You should be able to find easily the geometric proof that the cone is 1/3 the volume of the circumscribing cylinder.
Dec
2
comment Innovation behind formula for surface area and volume of a sphere
@Half-Bloodprince Also a standardized summation of simple shapes argument. Here is an example of derivation using a method of disks (which I don't like): mathforum.org/library/drmath/view/55263.html
Dec
2
answered Innovation behind formula for surface area and volume of a sphere
Oct
23
awarded  Nice Question
Oct
1
answered Find the point in this line such that the distance from $A$ is $\sqrt{3}$