Question

Check my answer?

What is the recursive rule for this geometric sequence?
−64,−16,−4,−1,...
Enter your answers in the boxes.


a n =
a 1 =

i think it is
an = a n + 1 * an-1
and
a1=-64
am i right?

Answer 1

A recursive rule for a geometric sequence

`a_1\\\\a_n=r\cdot a_(n-1)`

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`a_1=-64;\ a_2=-16;\ a_3=-4;\ a_4=-1;\ ...\\\\r=(a_(n+1))/(a_n)\to r=(a_2)/(a_1)=(a_3)/(a_2)=(a_4)/(a_3)\\\\r=(-16)/(-64)=(1)/(4)\\\\\boxed{a_1=-64;\qquad a_n=(1)/(4)\cdot a_(n-1)}`