Sequences & Series

Question 1

Arithmetic series

Answer 1

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

Question 2

Geometric series

Answer 2

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

Question 3

Geometric sum

Answer 3

S{n} = a(1-r^n) / (1-r)

Question 4

Arithmetric sum

Answer 4

S{n} = 0.5n[2a + (n-1)d]
S{n} = 0.5n(a+l)

Question 5

Geometric sum to infinity

Answer 5

S{n} = a/(1-r)

|r| < 1