Some mixed questions I need some confirmation on.

1:

Find (a) the directrix, (b) the focus and (c) the roots of the parabola .

I can find the directrix and the focus no problem, but i do not understand what they mean by "roots". Do they mean the roots(positive and negative) of the equation or something else?

2:

Write the first three terms of the expansion of .

Answer:

3:

What are the last three terms of ?

Answer:

Thank you!