Question

7th term of an AP is 40, then the sum of first thirteen term is

Answer 1

#BAL

Sum of n terms =n/2(1st term+ nth term). 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

Answer:

74.2857142

Step-by-step explanation:

first you should divide 40 with 7 equals to 5.71428571.

secondly you should multiply 5.7142857 with 13 equals to 74.285714

it is the answer .

ok! are you happy