I'm watching YouTube videos to teach myself some abstract algebra, a woman claims that integers under multiplication has a closed operation. But I do...

I've always been taught to write, for example, $$\sin^2(\theta)+\cos^2\theta \color{red}{\equiv} 1,$$ rather than $$\sin^2(\theta)+\cos^2\theta \colo...

Sorry if this question isn't valid. I just need to know an equation/function for a graph which resembles something close to

This could be primary school stuff. But I want to ask it. In factoring $x^2+bx+c$ (i.e. $a = 1$ in $ax^2+bx+c$), we find $m$ and $n$ such that $m+n = b$ a...

I am trying to study for a test and the teacher suggest we memorize $\sin(A+B)$, $\sin(A-B)$, $\cos(A+B)$, $\cos (A-B)$, and then be able to derive the re...

Suppose we are given an integral of the form $\int f(x) dx$ with $f(x)$ defined on $[a;b]$. We can then use inverse substitution using a function $g(t)$ d...

I recently pulled out my old Real Analysis textbook and noticed something that didn't stand out when I was taking the class all those years ago. When...

Find the fundamental period of $f(x)=\sec($sin(x)$)$. Choose the correct option. (A)$\frac{\pi}{2}$ (B)$2\pi$ (C)$\pi$ (D)Aperiodic We know the fundamenta...

Not sure if this is the right place to ask this but I searched and didn't find this question already asked. I am having a lot of trouble conceptually...

Evaluate $$\frac{1}{2!}+\frac{2}{3!}+\frac{3}{4!}+...+\frac{99}{100!}$$ My attempt, I changed it into $$\sum_{n=1}^{99} \frac{n}{(n+1)!}$$ I really don�...