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Apr
15
reviewed Approve suggested edit on Problem with trigonometric equation
Apr
15
answered Is my proof correct? Let $a, b, c\in\mathbb Z$. Prove that if $a\mid b$ and $b\mid c$, then $a\mid(b + c)$.
Apr
13
comment Finding the inverse of trig functions
Why would you need to find the inverse to calculate that?
Apr
13
comment How to show that there is no $3\times3$ real matrix $A$ such that $A^2+I=0$?
Note that such an $A$ does exist when $n=2$.
Apr
8
answered How to prove that $\sum_{k=0}^{n} \frac{k-1}{k!} =\frac{-n-1}{(n+1)!}$
Apr
8
answered Equation for power of a number.
Apr
7
comment Maclaurin Series expansion interval
You would write $$-\frac{1}{^5\sqrt{8}}<x< \frac{1}{^5\sqrt{8}}$$, or $$x \in \left[- \frac{1}{^5\sqrt{8}}, \frac{1}{^5\sqrt{8}}\right]$$
Apr
6
answered Maclaurin Series expansion interval
Mar
31
answered Prove the direct product of two subgroups is a subgroup
Mar
31
comment if $2^x+5^y=2^y+5^x=\frac{7}{10}$
Are $x,y$ assumed to be integers or real numbers?
Mar
28
comment Large Composition Operator?
Just be careful to explicitly define it that way, mostly to avoid confusion with notation like $\cos^{2}$, for instance.
Mar
28
answered Analytical question on year calculation.
Mar
24
answered Linear Maps: Why is it suffice to prove $T(u+av) = T(u)+aT(v)$?
Mar
23
comment Show that $\lim _{n \to \infty}\left (a_{n} + b_{n}\right) = a + b$ help ??
That's what we write, but it doesn't mean anything without a definition.
Mar
23
revised Show that $\lim _{n \to \infty}\left (a_{n} + b_{n}\right) = a + b$ help ??
Added LaTeX
Mar
23
comment Show that $\lim _{n \to \infty}\left (a_{n} + b_{n}\right) = a + b$ help ??
Do you know the definition of a limit?
Mar
23
comment Solutions to $x \sin x=1$ in the interval $0 < x \leq 2\pi$
For instance, observing that $f(x)$ is increasing on $(0,\pi/2)$ and decreasing on $(\pi/2),\pi)$.
Mar
22
answered Evaluating a limit with Mclaurin series
Mar
21
answered System of equations in polar coordinates $\dot{x}=x-y-x(x^2+y^2)+\frac{xy}{\sqrt{x^2+y^2}} \\ \dot{y}=x+y-y(x^2+y^2)-\frac{x^2}{\sqrt{x^2+y^2}}$
Mar
21
comment generating function for $\sum_{n=0}^{\infty} \{\sum_{i=0}^n {n \choose i}i^i (i-1)^{n-i}\}$
What sequence are you looking to generate, exactly?