3,919 reputation
11441
bio website
location
age 25
visits member for 3 years, 7 months
seen 7 hours ago

Sep
28
revised In $ \triangle ABC$ show that $ 1 \lt \cos A + \cos B + \cos C \le \frac 32$
Formatting
Sep
27
comment Theorem 20 Hoffman Kunze Linear Algebra book Section 3.6
@Care Bear Thank you.
Sep
27
answered Theorem 20 Hoffman Kunze Linear Algebra book Section 3.6
Sep
27
answered Task interpretation for Hoffman Kunze Linear Algebra exercise 1 (b) sec. 3.6
Sep
27
comment Classifying complex $2\times 2$ matrices up to similarity
Link to the hint.
Sep
27
revised Classifying complex $2\times 2$ matrices up to similarity
Improving formatting.
Sep
27
revised Matrix is either null or similar to the elementary matrix $E_{2,1}$
Improving title
Sep
26
revised Give example where an outer measure is strictly less than the set function from which it is defined.
Formatting
Sep
24
revised Showing $2 |f'(0) | \leq d$, where $f$ is some holomorphic function and $d$ is the diameter of $f$'s image?
added 1 character in body
Sep
24
revised Chapter 3, question 20 part b of Spivak's Calculus 3rd edition
edited body
Sep
24
comment Is the rank of a matrix the same of its transpose? If yes, how can I prove it?
The link no longer work for me.
Sep
24
revised Is the rank of a matrix the same of its transpose? If yes, how can I prove it?
deleted 3 characters in body
Sep
23
comment Prove that $\,f=0$ almost everywhere.
Use you establish that $\int_I f = 0$ for any subinterval of $[0,1]$, a quicker way to finish is by using Lebesgue's differentiation theorem.
Sep
23
comment How to prove a property of ranks
From what you have, it's enough to show that $$\dim\ker(AB) - \dim\ker B = \dim(\Im B \cap \ker A). $$
Sep
23
revised How to prove a property of ranks
Formatting. Fixing reference to wrong relation.
Sep
20
revised Presentation of a group: Show that $\langle a|a^2\rangle =\{1,a\}$.
Formatting
Sep
20
comment subspace of the Vector Space of real valued functions
You proved that $W$ is not a subspace of $\Bbb R^{\Bbb R}$. It's not a subspace of anything because $0\not\in W$.
Sep
19
revised Does $\lim_{n\to\infty}S_n \leq S$ imply that $S_n < S$?
formatting
Sep
10
comment Is there a power of 2 that, written backward, is a power of 5?
Related
Sep
9
answered Prove that $\sin(x+a), \sin(x+b),\sin(x+c), \hspace{5pt} a,b,c \in \mathbb{R}$ are linearly dependent