Translate these formulas into valid LaTeX:
---
vec x
==>
\vec{x}
---
| hat a cap vec b |
==>
\abs{\hat{a} \cap \vec{b}} 
---
reals^n
==>
\mathbb{R}^n
---
7n
==>
7n
---
j2
==>
j^2
---
j2
==>
j_2
---
limit h+ -> 0 of h
==>
\lim_{h_+ \to 0} h
---
USER_INPUT
==>
