Sorry for flooding this forum with weird questions... But as I went through the chapters I found more and more tough questions (maybe it's just tough for me)...

1. Find the coefficient of x^-12 in the expansion of (x³ - 1/x)^24.

For this question I don't know how to get the x^-12...

2.
a) Expand (2√2 + √3)^4 in the form a + b√6, where a and b are integers.
b) Find the exact value of (2√2 + √3)^5. (Answer: 698√2 + 569√3)

For question 2, I managed to get the answer for a) which is 217 + 88√6. But then I can't seem to get the answer for b)