Question

7th term of an ap is 40. the sum of its first 13th terms is

Answer 1

• Let the first term of an A.P. be a and common difference is d. So the 7th term of the A.P. is 40=> a+6d =40.

Sum of first 13 terms = 13/2(a +(a+12d))= 13/2(2a+12d) =

13/2(2)(a+6d) =13(a+6d) =13(40)=

520 .

Answer 2

Step-by-step explanation:

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