Question

if the sum of a certain number of terms of the A.P.25,22,19,......is 116,find the last term

Answer 1

a=25
d=-3
an=116
an=a+(n-1)*d
-116=25+(n-1)*-3
-116-25=(n-1)*-3
-141/-3=n-1
47=n-1
n=47+1
n=48