ARITHMETIC PROGRESSION-1

The 1st term of an A.P. is 78 and the common difference is 16. Find the 10th term.

Solution

A₁= 78, d = 20

A_n = A₁ + (n-1)d

A₁₀ = A₁ + (10-1)d

A₁₀ = A₁ + 9d

A₁₀ = 78 + (9x16) [ after substituting A₁= 78, d = 16 as given above]

∴ A₁₀ = 78 + 144

A₁₀ = 222

Hence the 10th term is 222.

TRY THIS……………

The 1st term of an A.P. is 30 and the common difference is 43. Find the 9th term.