Other Sequences with Formulas

CONCEPTS

Tips

• Explicit formula: a formula that does not require the value of the previous term

EXAMPLE

• Given aₙ = 2n + 3

• Recursive formula: a formla that does require the value of a previous term

EXAMPLE

• Given aₙ = aₙ₋₁ + n & a₁ = 1

PRACTICE PROBLEMS

Question 1 Given aₙ = aₙ₋₁ + 2n + 3 & a₁ = 2. What's a₄?

-- Answer -- 27

aₙ = aₙ₋₁ + 2n + 3 => a₂ = 2 + 2 (2) + 3 = 9

a₃ = 9 + 2 (3) + 3 = 18

a₄ = 18 + 2 * 4 + 3 = 27

ACT PRACTICE PROBLEMS

1/1

1/1