Question

find the sum of first 15 terms of an ap in which d=5 and 15th term is 75​

Answer 1

Answer:

tanvipilania25 it says i need 20 characs

Answer 2

Answer:

Let the first term and the last terms be a and l respectively.Let the number of terms be n

Hence,

a=5

l=75

n=15

We know,

Sum of n terms= n/2(a+l)

Sum of 15 terms=(15/2)(5+75)

= 15/2(80)

=15(40)

=600 ( answer)