maths&statistics 幾題數

1. expand the following in ascending powers of x as far as the term in x^3

(3+x)^5 (2+7x)^7

2. Find the term independent of x in the expansion

(x+4/x^3)^8

3. Find the 7th term in the expansion of (2x/3+y)^11 in desending powers of x

4. Find the coefficient of t^8 in the expansion of (t^2+3/t)^13

5. simplify (開方x + 3)^6 +(開方x -3)^6