Question

The first term of an ap 100 and last term -10 .Of the common difference is -2 how many terms are there and what is their sum.

Answer 1

Answer:

first use this formula to finding the n th term

an=a+(n-1)d

the use this formula

sn=n/2+(a+l)

an=last term

a=first term

n=total term

sn= sum of all term

d= common difference