Question

how would i find the first term of a geometric series when an=10, r=2, n=4?

thank you so much!

Answer 1

is an the same thing as the last term

Answer 2

according to my sheet, an is stated as the nth term

Answer 3

in geometric series, every term is equal to r*previous_term.
so if a1=x then a2=x*r a3=x*r*r a4=x*r*r*r so on. n-th is eqaul to a1*r^(n-1). 4-th term 10=a1*2^3 a1=10/8

Answer 4

if an is a4 then this is how its done:
10=a1(2)^4-1
So a1=10/8

Answer 5

thank you all so much!