Reputation
3,488
Top tag
Next privilege 5,000 Rep.
Approve tag wiki edits
Badges
2 11 39
Impact
~127k people reached

Oct
11
comment Solve $3\log_{10}(x-15) = \left(\frac{1}{4}\right)^x$
@abc: "closed form" solution means a formula using only elementary operations (addition, substraction, multiplication, division) plus a handful of functions (exponentiation, roots and logarithms, trigonometric).
Sep
30
comment Proving statement about dimensions of vector spaces
@Shahab: fixed it.
Sep
30
revised Proving statement about dimensions of vector spaces
blockquote messed up my latex
Sep
30
asked Proving statement about dimensions of vector spaces
Sep
30
comment arclength of vector r
You should mention that you can drop the absolute value because $t$ has to be positive.
Sep
29
accepted Help with a linear algebra problem; defining a function with some properties
Sep
29
comment Help with a linear algebra problem; defining a function with some properties
Well, I feel stupid now. It's $(-2,1,1)$. Everything works out now. Thanks!
Sep
29
comment Help with a linear algebra problem; defining a function with some properties
That's what you get if you solve the equations defining $f^{-1}(1,1,1)$. I don't understand your edit; $(-2,1,0)$ itself doesn't belong to $f^{-1}(1,1,1)$. You have to add $(-1,2,0)$ to it.
Sep
29
comment Help with a linear algebra problem; defining a function with some properties
I got there, but when trying to solve the system $f(x) = (1,1,1)$, I get something different than what it should be.
Sep
29
asked Help with a linear algebra problem; defining a function with some properties
Sep
28
comment How to solve $\cos(\pi/2+t)\ge 0$?
@Michael: your book has the same answer, it's just written complicated. Think about it; $t \in [\pi, 3\pi/2]$ or $t \in [3\pi/2, 2\pi]$ is the same thing as $t \in [\pi, 2\pi]$.
Sep
28
comment How do I integrate $\sqrt{x^2+81}$ using trig substitution?
Hyperbolic trig functions will work better in this case, probably.
Sep
27
answered Multivariable Partial Derivative
Sep
27
comment Multivariable Partial Derivative
Why can't you just calculate it, instead of trying to check all those options?
Sep
25
comment Solving simple modulus with a variable but use inegality operator
I don't know if you meant $1$ or $-1$, but in any case $|4x-2| \ge 1$ is equivalent to $4x-2 \le -1$ or $4x-2 \ge 1$.
Sep
25
comment Volume of a pyramid as a determinant?
@HenningMakholm: Well, it's probably a tetrahedron.
Sep
24
asked What is it called when a function is not continuous but still can have a derivative?
Sep
24
awarded  Citizen Patrol
Sep
23
comment What is the relevance of the supremum in this question?
@dukenukem: Pretty much. Sometimes the supremum is written a little differently, like this: $\displaystyle \sup_{x\in I}|f(x)-g(x)|$. But it's the same thing.
Sep
23
answered What is the relevance of the supremum in this question?