Sequences and Series (C20)

Question 1

What are recurrence relations?

Answer 1

Tells you how to find u k+1 from uk

Eg if each term is 2 more than the last, u k+1(small) = u k +2

So, for 1,3,5,7,9,11
u k+1 = u k+2(small)

Question 2

What is the formula for an arithmetic sequence?

Answer 2

Un = a+(n-1)r
a = first term
r = common difference 
Un = nth term

Question 3

What is the formula for a geometric sequence?

Answer 3

Un = ar^(n-1)
Un = nth term
a = first term
r = common difference

Question 4

What is the formula for a geometric series?

Answer 4

Sn = a(1-r^n) all over 1-r
Sn = nth term 
a = first term
r = common multiple

Question 5

What is the formula for an arithmetic series?

Answer 5

Sn = 1/2 n(a + l)
Sn = nth term 
a = first term 
l = last term