Question

The number of terms of the series -5 + 15 - 45 +. .... which makes the sum -305 is

(A) 3
(B) 5
(C) 7
(D) 9​

Answer 1

Answer:

Step-by-step explanation:

r=t2/t1=15/-5=-3

a=first term=-5

305=a(1-r^n)/1-r

305=-5(1-(-3)^n)/1+3

(305*4)/-5=1-(-3)^n

-244-1=-(-3)^n

243=-(-3^n)

n=5

PLEASE MARK BRAINIEST