ARITHMETIC PROGRESSION-1

Find the sum of the 1st 16 terms of the following arithmetic progression: 5+11+17+…………………

Solution

d=6, A₁ = 5,n=16

S_n = n[2A₁ + (n-1)d]

       2

S₁₆ = 16[2(5) + (16-1)d]

         2

S₁₆ = 8[10 + 15d]

 

S₁₆ = 8[10 + 15(6)]       since d=6

S₁₆ = 8[10 + 90]

           

S₁₆ = 8 x 100  

         

S₁₆ = 800

Therefore the sum of 1st 16 terms is 800.

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Find the sum of the 1st 16 terms of the following arithmetic progression: 6+14+22+…………………