ARITHMETIC PROGRESSION H1

 

The 1st term of an A.P. is 78 and the common difference is 45. Find the 10th term.

 

Solution

 

A₁= 78, d = 45

 

A_n = A₁ + (n-1)d

 

A₁₀ = A₁ + (10-1)d

 

A₁₀ = A₁ + 9d

 

A₁₀ = 78 + (9x45) [ after substituting A₁= 78, d = 45 as given above]

 

∴ A₁₀ = 78 + 405

 

A₁₀ = 483

 

Hence the 10th term is 483.

 

  

TRY THIS……………

 

 

The 1st term of an A.P. is 140 and the common difference is 23. Find the 18th term.