Reputation
488
Top tag
Next privilege 500 Rep.
Access review queues
Badges
3 5
Newest
 Enthusiast
Impact
~8k people reached

Mar
11
comment Finding the basis of a vector space $\Bbb{W}$
Instead of starting with a family of vectors that might be a basis, try starting with a single vector, then look for a second, linearly independent, vector, and so on. See the link given by Umberto P. (it even contains a complete answer).
Mar
11
comment Finding the basis of a vector space $\Bbb{W}$
What have you tried so far? Are there any particular points you have trouble with?
Nov
13
comment Addition in linear vector spaces
Addition of scalars is commutative even if much less than the full field axioms are given, e.g. in a quasi-field (multiplication neither commutative nor associative, only one distributive law), see math.stackexchange.com/questions/724122/…. Thus, to get non-commutative scalar addition, the requirements for the scalar structure would have to be relaxed considerably.
Oct
20
comment ZFC, NBG and Naive set theory
@AndresCaicedo: I stand corrected. If you submit an answer of your own, I'll retract mine.
Oct
17
answered ZFC, NBG and Naive set theory
Oct
16
comment Inverse image of a closed interval is compact
@jlang: No, the preimage of [0,1] under $f$ is a subset of $D$.
Oct
14
answered Prove that $S= \{ (x,y) : x^2 - y^2 <1 \}$ is open in $\mathbb{R}^2$
May
31
awarded  Enthusiast
Apr
25
comment If G is a finite abelian group and $a_1,…,a_n$ are all its elements, show that $x=a_1a_2a_3…a_n$must satisfy $x^2=e$.
What you have defined is obviously not a group. E.g. you've already seen that 22=6=42, but then (22)3=(42)3 and -- if associativity would hold -- 2=4.
Apr
24
answered 5 digit number $a6a41$ divisible by 9
Apr
11
answered Equivalence relation: prove that $(X \cap Y) $\ $E $ $\subset (X$ \ $E) \cap (Y$ \ $E)$
Apr
9
comment Equivalence relation: prove that $(X \cap Y) $\ $E $ $\subset (X$ \ $E) \cap (Y$ \ $E)$
Are you sure that you have written the inclusion in the right direction?
Apr
9
comment How do I find arccos(-16.503)
So, the problem seems to lie in an earlier step. How did you arrive at the expression $\arccos(-16.503)$?
Apr
4
comment cartesian product $A^2 = A$, possible?
Am I missing something, or should it be $A_\omega\times A_\omega\subset A_\omega$?
Apr
3
awarded  Yearling
Apr
3
comment Limit definition by ordinal numbers
Principia Mathematica, *207: "A term x is said to be the "upper limit" of alpha in P if alpha has no maximum and x is the sequent of alpha. In this case, x immediately follows the class alpha, though there is no one member of alpha with x immediately follows."
Apr
3
answered How multiple of number is determined?
Apr
2
comment Can two function $f$ and $g$ have same values through out a given interval and different values outside that interval?
@user136561: This merely shows the difference (within a certain interval) is smaller than the resolution of the computer monitor.
Apr
1
answered Show that for triangle ABC, with complex numbers for the coordinates, that we have the following equation
Apr
1
comment Why does $f(x)=ax^2 + bx + c \ge 0\ \forall x \in \mathbb R$ imply $f$ has at most one real distinct root and discriminant $D \le 0$?
@Sabyasachi: Take $a=1$, $b=c=0$.