Chapter 8

Question 1

0!

Answer 1

1

Question 2

∑i

Answer 2

N(N + 1) / 2

Question 3

∑i²

Answer 3

N(N + 1)(2N + 1) / 6

Question 4

∑i³

Answer 4

N²(N + 1)² / 4

Question 5

Arithmetic: a_N

Answer 5

a₁ + d(N - 1)

Question 6

Arithmetic: s_N

Answer 6

N/2 (a₁ + a_N)

or

N/2 (2a₁ + d(N - 1))

Question 7

Geometric: a_N

Answer 7

a₁r^{N - 1}

Question 8

Geometric: s_N

Answer 8

a₁(1 - r^N / 1- r)

Question 9

Infinite: s_∞

Answer 9

a₁ / 1 - r

Question 10

5!

Answer 10

5 ⋅ 4 ⋅ 3 ⋅ 2 ⋅ 1

Question 11

Alternating starting +

Answer 11

(-1)^{N + 1}

Question 12

Alternating starting -

Answer 12

(-1)^N

Question 13

When is a geometric sum infinite?

Answer 13

When r is greater than 0 and less than 1

Question 14

If in between a sequence: first count is the same

Answer 14

Arithmetic

Question 15

If in between a sequence: second+ count is the same

Answer 15

Squared, cubed, ect.