Question

Find sum of 7+10.5+14.........+84

Answer 1

Answer:

1046.5

Step-by-step explanation:

It is in series

a=7 n=?

last term =84

d=3.5

l=a+(n-1) d

84=7+(n-1) 3.5

77=3.5(n-1)

22 =n-1

n=23

now we have to find sum if all terms

sum=n/2(a+l)

sum=23/2(7+84)

sum=23*91/2

sum=23*45.5

sum=1046.5