9,568 reputation
11338
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location United States
age 24
visits member for 2 years, 9 months
seen 29 mins ago

20m
revised What is the remainder on division of $z^{400} + z^{303} + 1$ by $z^4-1$?
edited title
28m
reviewed Approve suggested edit on Show that the unit sphere with centre $0$ in $\mathbb{R}^d$ is compact.
31m
comment Given that $f(1)=1$, $f'(1)=-1,$ calculate $\int_0^t f(\alpha) \,\mathrm{d}\alpha$.
I'm not convinced that there is a unique solution to this..
40m
comment Is $I=\langle7, 3+\sqrt{19}\rangle$ a principal ideal of $\Bbb Z[\sqrt{19}]$?
$\LaTeX$ formatting comment: you should maybe use \langle and \rangle in place of $<$ and $>$ in this context.
41m
revised Is $I=\langle7, 3+\sqrt{19}\rangle$ a principal ideal of $\Bbb Z[\sqrt{19}]$?
added 12 characters in body; edited title
43m
revised Equiangular hexagon problem
edited body; edited title
13h
comment Embedding a ring into a ring with unity
It can also be viewed somewhat as both rings acting on each other.
14h
answered Points, Slopes and Intercepts
17h
reviewed Approve suggested edit on Solving a differential equation 1st order
17h
comment Can anyone help me with this proof of matrix?
This is pretty difficult to understand. Are you trying to say that $A = A^2 = -I$?
17h
reviewed Approve suggested edit on Find the least $n$ such that the fraction is reducible
17h
reviewed Approve suggested edit on Reproducing kernel Hilbert space, Inner Product
17h
reviewed Reject suggested edit on Find points in a reference unit square
22h
comment I wonder where did I go wrong with deciding if these sequences are increasing (I), decreasing (D), both (B), or neither increasing nor decreasing (N)
No problem :) Glad to help.
23h
comment I wonder where did I go wrong with deciding if these sequences are increasing (I), decreasing (D), both (B), or neither increasing nor decreasing (N)
There is a difference between both and neither. Both means that $a_n \le a_{n+1}$ and $a_{n+1}\le a_n$ (i.e. it's a constant sequence..). Neither means that the function strictly increases for part of the sequence and strictly decreases for part. Particularly, I would say 1 is both and 2 is neither. Can you take it from there?
1d
comment Is there a rigorous proof for the existence of complex number?
Well what definition of complex numbers are you interested in? Some definitions make it clear that they exist (by definition).
1d
comment Show that if $G$ is cyclic then so is $H$
Suppose $G$ is generated by $g$, what can you say about $f(g)$?
Oct
28
reviewed Approve suggested edit on Finding min's and max's of equations
Oct
28
comment Inverse of a Function exists iff Function is bijective
@user3813179 Induction is definitely a no-go here. Induction requires a countable set but you can have functions defined on uncountable sets.
Oct
28
comment Why do oscillating sequences diverge?
The way I like to think of it is that a sequence converges if every subsequence converges to the same value.