Log in to add a comment

Log in to add a comment

Step 1: Find the difference using the given term a₂ = 15.

a₁₅ = a₁ + (n-1) (d)

15 = a₁ + (2-1) (d)

15 = a₁ + 1d

a₁ = d - 15

a₉=39

39 = d-15 + (9-1) (d)

39 = d-15 + 8d

39 = 9d - 15

9d = 39 + 15

9d/9 = 54/9

Step 3: Find a₁.

a₁ = ?

d = 6

a₂ = 15

15 = a₁ + (2-1) (6)

15 = a₁ + 6

a₁ = 15-6

Step 3: Find a₁₆.

a₁₆ = 9 + (16-1)(6)

a₁₆ = 9 + (15)(6)

a₁₆ = 9 + 90