Sandbox

Test test

FTFY: If $$f:X\to Y$$ is a function from $$X$$ to $$Y$$ and $$A\subset Y$$, then $$f^{-1}(A)=\{x\in X:f(x)\in A\}$$ is the preimage of $$A$$ under $$f$$.

$$e=mc^2$$

$$e=m(a^2 + b^2)$$

(Einstein-Pythagoras Theorem)

\frac{1}{x} \sum_{n=1}^\infty \frac{1}{n^2} = \pi^2/6 <\math> vdvdvsd