# (1) Find first five terms f the following sequences? (2) Given first few terms find the explicit formula for #n^(th)# term?

##
1(a) #f(n)=(-1)^n(2n+1)/n^2#

1(b) #f(n)=sin((3pi)/n)/n#

2(a) #{1,1/2,1/6,1/24,1/120,.}#

2(b) #{3,3/2,1,3/4,3/5,.}#

2(c) #{1,-sqrt7,7,-7sqrt7,.}#

1(a)

1(b)

2(a)

2(b)

2(c)

##### 1 Answer

Please see below.

#### Explanation:

**1(a)** As

or

**1(b)** As

or

**2(a)** We have first five terms as

Hence formula is

**2(b)** We have first five terms as

Hence formula is

**2(c)** We have first five terms as

Therefore, it is a geometric sequence with first term as

Hence formula is