Question

Find the 45th term of arithmetic sequence -9,-2,5,12.

Answer 1

Concept:

An arithmetic progression is a sequence of numbers such that the difference between the consecutive terms is constant. For example, the sequence 5, 7, 9, 11, 13, 15.. . is an arithmetic progression with a common difference of 2

General term of arithmetic progression,

aₙ = a₁ + (n-1) d

Given:

Arithmetic sequence of -9,-2,5,12.

Find:

Find 45th term of the arithmetic sequence

Solution:

a₁ = -9

d = 7

n = 45

By using the formula for general term of arithmetic progression,

aₙ = a₁ + (n-1) d

Substituting the terms:

⇒a₄₅ = -9 + (45-1) (7)

⇒a₄₅ = -9 + 308

⇒a₄₅ = 299

Therefore, 45th term is the sequence is 299

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