Question

what is the nth term? -1+2+(-4)+8+...
A) (-2)^n
B) (-2) ^n-1
C) (-1)^n (2)^n-1
D) (-1)^n (2)^n+1

Answer 1

a = -1 r = -2

\[T _{n} = ar^{n-1}\]

just substitute as this is a geometric series

Answer 2

so would it be C?

Answer 3

looks like it

Answer 4

thanks!