Question

Which is the equation for the nth term of the geometric sequence: -4,8,-16...?

Answer 1

aₙ=(-2)ⁿ*2.

Explanation:

1) -4*(-2)=8; 8*(-2)=-16; -16*(-2)=32, ...

2) the required equation is:

aₙ=(-1)ⁿ*2ⁿ*2; ⇒ aₙ=(-2)ⁿ*2 or aₙ=(-1)ⁿ*2ⁿ⁺¹.