User:Anatanson/Sandbox

The first statement is:
 * $ \frac{2,3} + \frac{3,4} = \frac{17,12}. $

The second statement is:
 * If $x$ is an integer, then $x^{2 + 3} = (x^2)(X^3)$.

The third statement is:
 * If $n \in \NN$, and $n \geq 1$, then $\sum_{i=1}^{n+3} i = ((+3)(n+4))/2$.