SOLUTION: I just don't even know what to say..................help!!!!!!!!!!!!!!!!! Given the following recursively defined sequence, find the fifth term. a_1 = -4 a_2 = -4 a(

SOLUTION: I just don't even know what to say..................help!!!!!!!!!!!!!!!!! Given the following recursively defined sequence, find the fifth term. a_1 = -4 a_2 = -4 a(_n+2)= a(

Question 43317: I just don't even know what to say..................help!!!!!!!!!!!!!!!!!
Given the following recursively defined sequence, find the fifth term.
a_1 = -4
a_2 = -4
a(_n+2)= a(_n+1)-4a_n
a. 28
b. 764
c. -20
d. -308
e. None of the others

Found 2 solutions by fractalier, psbhowmick:
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
This isn't as hard as you think...from
a_(n+2)= a_(n+1) - 4a_n
you merely plug in a_1 = -4 and a_2 = -4 to find a_3...
a_3 = -4 - 4(-4) = 12 now continue
a_4 = 12 - 4(-4) = 28
a_5 = 28 - 4(12) = -20
Choice C.
Answer by psbhowmick(878) (Show Source): You can put this solution on YOUR website!

Now,

When, n = 1,

or
or

When, n = 2,

or
or

When, n = 3,

or
or

Hence, (c) is correct.