How many triangles can we form if we draw all the diagonals of a hexagon? I thought that the answer is $\binom{6}{3}=20$ but this is not the right answer,...

According to page 2 of this document, $\tan\theta=(y/x) \nRightarrow \theta=\tan^{-1}(y/x)$. Example question: Convert the point $(\sqrt{2},-\sqrt{2},4)$ ...

It's my 3rd time going through Calculus II and I want to pass this class already. I'm not trying to cheat I just see people with fancy calculato...

Use Descartes' rules of signs to discuss the possibilities for the roots of each equation. Do not solve equation. $$p(x)= x^3+5x^2+7x+1=0$$ $p(x)$ I ...

Here is example of some planar lamina; non-convex, but without self-intersections. I'd like to define some "my" center of lamina that will be always ...

I am trying to find the derivative of $\sqrt{9-x}$ using the definition of a derivative $$\lim_{h\to 0} \frac {f(a+h)-f(a)}{h} $$ $$\lim_{h\to 0} \frac {\...

I want to be able to use Stirling Series to approximate n! inputing a vector. So far, I can do this entry wise. And I'm not sure why I cannot input a...

If we take the implicit derivative of $x^3+x^2-y^2=0$, we find that $\frac{dy}{dx}=\frac{3x^2+2x}{2y}.$ So, the slope of the tangent line should be undefi...

When matrices are row equivalent... why is this important? If a matrix like: $$\begin{bmatrix} 1 & 0 \\ -3 & 1 \end{bmatrix}$$ is row equivalent t...

I'm studying two algebraic topology texts (namely Munkres and Theodore) Here are definitions given in those texts Munkres Let $X$ be a topological sp...