Question

The following function defines a recessive sequence:

f(0) = -4
f(1) = 12

f(n) = -3•f(n -1) - 2•f(n - 2); for n > 1

Which of the following sequences is defined by this recursive function?


A) -4, 12, -28, 60, …
B) -4, -12, -28, -60, …
C) -4, 12, -18, 54, …
D) -4, 12, -18, -54, …

Answer 1

`f(0)=-4\\f(1)=12\\\\f(n)=-3f(n-1)-2f(n-2)\\\\f(2)=-3f(2-1)-2f(2-2)=-3f(1)-2f(0)=-3\cdot12-2\cdot(-4)\\=-36+8=-28\\\\f(3)=-3f(3-1)-2f(3-2)=-3f(2)-2f(1)=-3\cdot(-28)-2\cdot12\\=84-24=60\\\\Answer:A)\ -4;\ 12;-28;\ 60;...`