Question

the first term in the last term of an ap are 8 and 350 respectively if it's common difference is 9 how many terms are there in what is this sum

Answer 1

give that last term=350 so there are 350 terms
s=n/2(2a+(n-1)d)
where n= no of terms=350
a is the first term=8
d is the difference =9
s=350/2(2*8+(350-1)*9)
=552,475
sum of the terms =552,475


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Answer 2

We have,

a is 8, l is 350 and d is 9.

We have to find the number of the terms i.e., n

And, also we have to find the sum of the n terms .

So,

350 = 8 + (n-1)9.

= 342 = 9(n-1).

= n-1 = 38

n = 39.

Now,

Sum of 39 terms = 39/2(358)

Sum = 179 × 39 = 6981.