Question

which choice is the explicit formula for the following geometric sequence 0.5,-0.1, 0.02, -0.004, 0.0008

Answer 1

Hello,

Answer is C

`a_1=0.5=(1)/(2) \\\\a_2=-0.1=-(1)/(10) =a_1*(-(2)/(10) )=a_1*(-(1)/(5) )\\\\a_3=0.02=(2)/(10^2) =a_2*(-(2)/(10) )=a_2*(-(1)/(5) )=a_1*(-(1)/(5) )^2\\...\\a_n=a_1*(-(1)/(5) )^(n-1)\\\\\boxed{a_n=0.5*(-0.2)^(n-1)}\\`