Question

A progression has a first term of 12 and a fifth term of 18.

Find the sum of the first 25 terms in the progression is aritmetic.

Answer 1

If th progression is an AP!
Then a = 12 and a+4d = 18
So d = 6/4 = 3/2 = 1.5
So sum can be found by
S = n/2(2a+(n-1)d)
You have
a = 12
d=1.5
n = 25
Just put it in the equation and then SOLVE!! :)
Getting me? :)

Answer 2

ummm im ok :) it'll take me a bit to understand could i get back to you ?

Answer 3

Perfect ! i get it ! thanx a lot

Answer 4

:)