![What is the variance of a constant? [closed]](https://news.conceivablytech.com/uploads/what-is-the-variance-of-a-constant-closed_720.jpg)
general
What is the variance of a constant? [closed]
Given a constant $c$, I know that $\text{E}(c)=c$, but what about the variance of $c$?
Apr 18, 2026
Archive: General
general
Find intersection point of two straight lines
I want to find the intersection point of two lines where, one of the lines is parallel to y axis. I know we can find the intersection point of two line by...
Apr 18, 2026
general
Where did I go wrong differentiating arccos(4/x)?
I've been trying to differentiate $y=\arccos(4/x)$ and ended up with the answer $\frac{dy}{dx} = \frac{4}{x\sqrt{x^2-16}}$ however the solution to th...
Apr 18, 2026
general
Geometric interpretation of cross & dot product relation
May be simple, but how is each term geometrically interpreted in a comprehensive diagram? We have a Pythagorean relation between dot and cross products he...
Apr 18, 2026
![Simplify $\sqrt{8-\sqrt{63}}$ [duplicate]](https://news.conceivablytech.com/uploads/simplify-sqrt-8-sqrt-63-duplicate_720.jpg)
general
Simplify $\sqrt{8-\sqrt{63}}$ [duplicate]
I simplified the expression into $$\sqrt{8-3\cdot \sqrt{7}}$$ but my tutor said it wasn't the answer he was looking for. Can someone help me?
Apr 18, 2026
general
How to tell whether two graphs are isomorphic?
Suppose that we are given two graphs on a relatively small number of vertices. Here's an example: Are these two graphs isomorphic? (That is: is there...
Apr 18, 2026
general
How do I tell if matrices are similar?
I have two $2\times 2$ matrices, $A$ and $B$, with the same determinant. I want to know if they are similar or not. I solved this by using a matrix called...
Apr 18, 2026
general
A and B are mutually exclusive, C and D are independent
Another GRE study question Let A, B, C, and D be events for which P(A or B) = 0.6, P(A) = 0.2, P(C or D) = 0.6,and P(C) = 0.5. The events A and B are mutu...
Apr 18, 2026
general
When can you treat a limit like an equation?
Lately, I've been very confused about the weird properties of limits. For example, I was very surprised to find out that $\lim_{n \to \infty} (3^n+4^...
Apr 18, 2026
general
Discrete Dirichlet problem. What's wrong with my solution?
I'm reading Artin's Algebra and stumbled upon this miscellaneous question. Chapter 1 Excercise M11. I will post the problem here. This is my pro...
Apr 18, 2026
