Question

Find the sums given below:
(1)
7 +10 1/2 +14+.... +84​

Answer 1

Answer:

first term(a)=7 and common difference(d) = second term- first term = 10(1/2)- 7= 7/2 now first we need to find total number of terms to find sum. i.e n therefore last term(l) = a+(n-1)d 84=7+(n-1)7/2 84-7= (n-1)7/2 77*2/7= (n-1) 22= n-1 n= 22+1 n=23 so total term is 23 now put all values in formula to get sum sum= n/2(a+l) 23/2(7+84) 23/2*91= 1046.5 or 1046(1/2)ans.