Question

Find the first, fourth, and eighth terms of the sequence. A(n)= -2 x 5^n-1

Answer 1

You've got
$A(n)=-2(5)^{n-1}$

just sub the number of the term to findd the term
first term is A(1)=-2(5)^(1-1)=-2(5)^0=-2(1)=-2
4th is A(4)=-2(5)^(4-1)=-2(5)^3=-2(125)=-250
8th term is A(8)=-2(5)^(8-1)=-2(5)^7=-2(78125)=-156250