Question 121

The sum of the first 10 terms of the progression 2, 5, 8, 11, .... is

Solution

Solution 

Sum of A.P. = $$\frac{n}{2}$$ (2a + (n-1)d)

Here, a = 2

         d = 8 - 5 = 5 - 2 = 3

and A/q n = 10.

Putting the values in the Formula

S = $$\frac{10}{2}$$ (2 x 2 + (10-1)3)

  =5 (4 + 27)

= 5 x 31 

= 165 Answer


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