Question

Find the 25th term of the following Arithmetic sequences a) -4,-1, 2, 5... b) 6.1₁ 7. 2, 8.3,...​

Answer 1

(a) 68 , (b) 32.5

Explanation:

the nth term of an arithmetic sequence is

`a_(n)` = a₁ + d(n - 1)

where a₁ is the first term and d the common difference

(a)

here a₁ = - 4 and d = a₂ - a₁ = - 1 - (- 4) = - 1 + 4 = 3 , then

a₂₅ = - 4 + (3 × 24) = - 4 + 72 = 68

(b)

here a₁ = 6.1 and d = a₂ - a₁ = 7.2 - 6.1 = 1.1 , then

a₂₅ = 6.1 + (1.1 × 24) = 6.1 + 26.4 = 32.5