A. P. 1

The 1st term of an A.P. is 90 and the common difference is 34. Find the 10th term.

Solution

A₁= 90, d = 34

A_n = A₁ + (n-1)d

A₁₀ = A₁ + (10-1)d

A₁₀ = A₁ + 9d

A₁₀ = 90 + (9x34)   [after substituting A₁= 90, d = 34 as given above]

∴ A₁₀ = 90 + 306

A₁₀ = 396

Hence the 10th term is 396.

TRY THIS……………

The 1st term of an A.P. is 60 and the common difference is 35. Find the 14th term.