MI + binomial thm

1.(a)prove by mathematical induction that 2+4 6+...+ 2n =n(n+1) for all positive integers n.
(b) hence, prove that 1+3+5+...+ (2n+1)=n^2 for all positive integers n.

我識做a,,但係唔知點樣運用到a黎做b,,因為題目用左hence,,所以如果就咁獨立兩題做ge話,,我就識做,,所以淨係做到b就ok了

2.determine whether the expansion of (3x+ 2/(x^2) ) ^8 consists of
(a)constant term
(b) an x^2 term
(c) an x^4 term

3. does the expansion of (3x- 2/x ) ^6 contain the term in x^5