Question

Use the formula for the sum of the first n terms of a geometric sequence to solve. Find the sum of the first four terms of the geometric sequence: 2, 10, 50, . . .
okay so my problem with this is it is in word problem form

Answer 1

so n= 4
and r= 5

Answer 2

and a1 = 2
right

Answer 3

Yes. Continue.

Answer 4

so then when I plug those in I get 312

Answer 5

Do you know the formula that you need?