Question

in an AP the first term is -5 and last term is 45.if the sum of all the terms is 120,then find n​

Answer 1

Answer:

sum=n/2(a+l)

120=n/2(-5+45)

240=n(40)

n=240/40

n=6

Answer 2

Answer:

n=6

Step-by-step explanation:

a= -5

l= 45

sum of all term =120

n=?

sum of all term= n/2[a+l]

120=n/2[-5+45]

120=n/2(40)

120/40=n/2

3×2=n

n=6