SOLUTION: Can you help me understand how to approach this sequence: 3, -6, 12, 4, 20, ?

Question 965862: Can you help me understand how to approach this sequence:
3, -6, 12, 4, 20, ?
Answer by Edwin McCravy(20054) (Show Source): You can put this solution on YOUR website!
3, -6, 12, 4, 20,


Look at the red numbers below.  They go -9,-8,-7,-6,...
Look at the blue numbers below. They go 18,16,14,12,... 

3 + -9 = -6
         -6 + 18 = 12
                   12 + -8 = 4
                             4 + 16 = 20
                                      20 + -7 = 13
                                                13 + 14 = 27
                                                          27 + -6 = 21
                                                                    21 + 12  

Notice also that each blue number is -2 times the preceding red number.

Edwin

RELATED QUESTIONS
Can you help me understand how to do this problem. 63x^3 - 35x^2 + 36x - 20= Thanks (answered by Fombitz)

Can you help me to understand how to solve this equation? 2x-3[x+4(5-2)] Thank you! (answered by mananth)

I have been struggling with this equation for 3 days, and can not understand what I am... (answered by MathLover1)

Sequence: 3, -6, 12, -24, 48,..., find S(sub 20). If S(sub 0)= 3. Then find the sum... (answered by ewatrrr)

Can you help me understand how to start/solve this number series problem? (10 * 4/2),... (answered by MathLover1,greenestamps)

y+4=-2/3(x-6) can you simplify this? I am trying to learn slope-intercept form by myself. (answered by ReadingBoosters)

I'm trying to find the sequence for this 3, -6, 12, 4, 20,... (answered by ikleyn)

I'm trying to find the sequence for this 3, -6, 12, 4, 20,... (answered by Alan3354)

Can you, please, help me write this sequence of numbers in summation notation? Thank you! (answered by Boreal)