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Apr
18
awarded  Yearling
Apr
15
comment Volume of a pencil
Your first equation is correct, but you haven't factored out the 2 properly in the second one.
Apr
15
comment Volume of a pencil
Substitute $110 - h$ for $x + y$ and manipulate. You know the equation you are trying to reach, so it shouldn't be too hard to get there.
Apr
15
answered Volume of a pencil
Apr
5
comment Notation — How do I denote the derivative of a reciprocal evaluated at some value?
OK, so instead do $(\frac{1}{f})^\prime(0)$?
Apr
5
comment Notation — How do I denote the derivative of a reciprocal evaluated at some value?
How about $(f^{-1})^\prime(0)$?
Apr
1
comment Is there a difference between $x=0$ and $0=x$
Equality is symmetric, so if $a = b$ then $b = a$. The statements are different, but logically equivalent.
Mar
28
answered Linear Algebra Orthogonality Proof
Mar
28
comment If the positive series $\sum a_n$ converges does $\sum a_n \log(a_n)$ converge?
It still works as $\log \frac{1}{n \log^2 n} = - \log n - \log \log^2 n$
Mar
28
answered If the positive series $\sum a_n$ converges does $\sum a_n \log(a_n)$ converge?
Mar
23
answered Partitioning the edges of $K_n$ into $\lfloor \frac n6 \rfloor$ planar subgraphs
Mar
23
comment Finding if the orthonormal basis of P1 with a given inner product
The zero vector can never be in a basis. Take $1,t$ and do Gram-Schmidt.
Mar
20
comment Rudin 1.11 Lower Bounds
Since the ordered set specified is $S$, the intention was "bounded below in $S$".
Mar
20
comment Rudin 1.11 Lower Bounds
In your example, $B$ is not bounded below in $S$.
Mar
12
comment If $A,B\in M_2(\mathbb{R})$, show that $(AB-BA)(AB-BA)$ is a scalar matrix.
Do you know the Cayley-Hamilton theorem?
Mar
5
comment Do $A$ and $p(A)$ have the same eigenvectors?
What if $c_i = 0$?
Mar
5
comment Should I be concerned if I cannot solve most exercises in my textbook?
I suppose it depends. How long are you trying problems before giving up? Do you feel like the proportion of problems you can solve without checking the solutions is increasing? etc...
Feb
21
comment T/F: any number that can be written as a fraction is rational.
What about $\frac{\sqrt{2}}{2}$?
Feb
18
comment Given the determinant determine the value of the matrix
What have you tried? What properties of determinants do you know?
Feb
17
answered Show that $\binom{2n}{n}+\binom{2n}{ n-1} = {1\over2}\binom{2n+2}{n+1}$