general
How to use the power series of $e^x$ to find the derivative of $e^x$?
I am currently reading Roger Penrose's The Road to Reality and in the book, the author poses various problems with three different levels of difficul...
Apr 10, 2026
Archive: General
general
How many sets of numbers can we find?
We have the following set of numbers $1,2\dots14$. a) How many subsets with 4 numbers can we find that contain only one even number b) How many subsets wi...
Apr 10, 2026
general
What does "X% faster" mean?
I was reading something today that was talking in terms of 10%, 100% and 1000% faster. I assumed that 10% faster means it takes 10% less time (60 seconds ...
Apr 10, 2026
general
Canonical Prime Factorisation
The Fundamental Theorem of Arithmetic states that every integer $n > 1$ can be uniquely expressed as a product of prime powers, that is: $$n = p_1^{n_1...
Apr 10, 2026
general
How to know if you are "tough enough" to study Algebraic Topology [closed]
I am graduating with a BA this summer and I am very interested in topology. I admit it, I never went that deep into topology and all I know is about point...
Apr 10, 2026
general
Is there $\phi(n)=n/6$
I know how to find for which $n$ $\phi(n)=n/2$ or $\phi(n)=n/3$, my method for finding those was simply to find primes $p$ that satisfy $\Pi_p$$_|$$_n$$1-...
Apr 10, 2026
general
Which units describe the area under a curve?
A car traveling in a straight line from its starting position at a speed of $65 $ miles per hour for $3$ hours is represented by the function $v(t)$ where...
Apr 10, 2026
general
Find the value for z(0.1) from a distribution table?
I'm doing a statistics course, and I thought I had no problems using distribution tables to find values. For example, for the Gauss distribution, if ...
Apr 10, 2026
general
Vector Projection XY plane
How do I find orthogonal projection of a vector $\vec V_1=(2,3,4)^T$ formed with the points $A(0,0,5)$ and $B(2,3,9)$ on $xy$ plane?
Apr 10, 2026
general
Set, n-Tuple, Vector and Matrix — links and differences
I know this question has been asked like 1000 times, however all supplied answers were not really satisfying to me. My question concerns the similarities ...
Apr 10, 2026
