If the first term of an AP is 2 and the common difference is 3,find the sum of the (1) first time
(2) first twelve times ​

-15

Step-by-step explanation:

using our basic formulas

S(11) = (11/2)(4 + 10(3))

= 187

t2 = ar = -6

t5 = ar^4 = 48

divide them:

r^3 = 48/-6 = -8

r = -2

in ar = -6

a = 3

sum(4) = a(r^4 - 1)/(r-1)

= 3((-2)^4 - 1)/(-2-1)

= 3(15)/-3

= -15

check:

first 4 terms are:

3 , -6, 12, -24

add them to get -15

step-by-step explanation: