sequence and series

Question 1

recurrence relation equation

Answer 1

U(n+1) = aU(n) + b

Question 2

Arithmetic sequence

Answer 2

U(n) = a + (n-1)d

Question 3

Geometric sequence

Answer 3

U(n) = ar^(n-1)

Question 4

4
Σ 3r
r=1

Answer 4

First term- sub in first value of r e.g 3
Common difference - sub in first three values for r e.g. 3
No.terms - n-(r+1) [where n is the number above the sigma notation] e.g. 2