oka so the question is as follows:

Question

for the geometreic sereis 8+48+288+... find the sum of the first ten terms, s 10

so I would use the formula:
sn= a(1-r^n)/ 1-r
were
a= 8
r= 48
n= 10

8(1-(48)^10)/1-48

I get lost I don't know how to arrive to the answer from here! but is the rest correct?

No. r is 6. Notice 8*6= 46, 48*8= 288, etc.

Other wise, it is ok.