Question

The first term of AP is -5 and last term is 45 .If sum f ap is 120.then find no. Of termand d

Answer 1

Answer:

number of term is 6 and difference is 10

Step-by-step explanation:

120=n/2(a+l)

120=n/2(-5+45)

120=n/2(40)

120=20n

n=120/20

n=6

120=6/2(2×-5+(6-1)d)

120=3(-10+5d)

-10+5d=40

5d=40+10

5d=50

d=10