What do you do to reflect a shape over a X-axis when it touches/goes past the axis???

Answer 1

You just make the negative part positive, and the positive part negative.

For example if you had a graph like this:
........ /
....... /
...... /
<---/--------> x axis
.... /
... /
.. /

The reflection would be:
.. \
... \
.... \
<---\--------> x axis
...... \
....... \
........ \

Answer 2

You would reflect what's above the x-axis to under it, and what's under it to above it.

so something that looks like
---/\---
would be
---\/---
where --- is the axis