you are so smart! how did you get x[2]=5?

來源: 於 2010-01-10 16:19:25 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

I use generalizing...

X[n+1]- X[n]= 2(X[n]- X[n-1])

thus,

X[n+1]- X[n]
=2*2(X[n-1] - X[n-2])
=2^3(X[n-2] - X[n-3])
=2^4(X[n-3] - X[n-4])
....
=2^(n-1)(X[2] - X[1])

for X1=3 Thus, X2=???


for n=19, X[20]-X[19] = 2^19(?-3)