ebaines
Jan 20, 2014, 06:58 AM
Hint: take the difference of pair of numbers in the sequence. Then take the differences of each pair of differences, etc. Eventually you'll come across a pattern that you can work backwards to find the next number. This technique works on any sequence that derives from a nth-order equation - in this case the underlying equation is a cubic.
burgess87
Jul 21, 2014, 11:49 PM
I tried to solve this puzzle but failed..
I am very excited to know this pattern..
Somebody please answer this question
ebaines
Jul 22, 2014, 05:39 AM
Starting with the sequence: 4, -4 , -9, -4, 18, 64
the differences bewtween each pair are:
A) -8, -5, 5, 22, 46
And the differences between these differences are:
B) 3, 10, 17, 24
Finally, the differences between these are:
C) 7, 7, 7
So - we conclude that the next number in series C is 7:
C) 7, 7, 7, 7
which means the next number in series B is 24+7=31:
B) 3, 10, 17, 24, 31
and the next numner is series A is 46+31 = 77:
A) -8, -5, 5, 22, 46, 77
Finally, the next number in the main sequence is 64+77 = 141:
4, -4, -9, -4, 18, 64, 141