Write a recursive rule for this sequence:
4, 12, 36, 108, 324.....

Question

Write a recursive rule for this sequence:
4, 12, 36, 108, 324.....

anonymous · Answer

it's being multiplied by 3 each time

parthkohli · Answer

Looks like it's a normal geometric sequence.

parthkohli · Answer

We have the common ratio = 3 and first term = 4.$$T_n = T_1\times r^{n-1 } $$The most you can do here is substitute $T_1$ with $4$. That leaves you with$$T_n = 4r^{n - 1} $$

amistre64 · Answer

T is used conventionally to determine the triangular numbers; A is used as a generic ... not that it matters ;)

parthkohli · Answer

Sorry, Amistre. My apologies :)

amistre64 · Answer

the rule should have 2 parts; defining inital terms and defining the relation between successive terms

amistre64 · Answer

getting the first term to a 1 or a zero is usually helpful in picking out a pattern