Question

Which term of the AP :18,23,28,33,...is 98?

Answer 1

17 term

Explanation:

the nth term of an arithmetic progression is

`a_(n)` = a₁ + d(n - 1)

a₁ is the first term, d the common difference, n the term number

here a₁ = 18 and d = a₂ - a₁ = 23 - 18 = 5

substitute these values into the nth term formula

`a_(n)` = 18 + 5(n - 1) = 18 + 5n - 5 = 5n + 13

equate 5n + 13 to 98 and solve for n

5n + 13 = 98 ( subtract 13 from both sides )

5n = 85 ( divide both sides by 5 )

n = 17

98 is the 17th term