Question

how many terms of the ap 17,15,13,11.... must be added to get the sum 72​

Answer 1

Answer:

Hey met here is your answer,

Given: a=17

          d = -2

         Sn = 72

Too find : n=?

Step-by-step explanation:

Using the formula,

Sn=n/2[2a+(n-1)d]

72=n/2[2*17+(n-1)(-2)

72=n/2[34-2n +2]

72*2/n=36-2n

144/n=2(18-n)

144/2n=18-n

72/n=18-n

Hope my answer will help you..