Question

Find the number of terms in an A.P. 18,15,12,……., – 48 and also find the sum of all

of its terms. in n

answer is available in picture​

Answer 1

Answer:

Step-by-step explanation:

a= 18

d=-3

l = -48

l = a+(n-1)d

-48 = 18+(n-1)(-3)

-48-18 = (n-1)(-3)

-66= (n-1)(-3)

n-1 = 22

n= 23