Saturday, 15 December 2012

proof writing - Prove inequality using induction with a sequence



The sequence is defined as dn=1 if n=0, ndn1 otherwise. The goal is to prove nZ+,d2n12n1 using induction. I successfully proved the base case, and laid out the induction step: assume d2k12k1 prove d2k+12k+1 But I am now struggling to algebraically prove the later inequality. I expressed d2k+1 in terms of d2k1:
d2k+1=(2k+1)d2k12k But I do not see any steps I can take from here. Any help is appreciated! I am new to this resource, please let me know if I formatted anything incorrectly!


Answer



Starting from
d2k12k1
multiply both sides with 2k+1 and you will get
2kd2k+1=(2k+1)d2k1(2k+1)2k1

Divide both sides by 2k:



d2k+12k+1(2k1)(2k+1)2k2k+14k214k22k+1


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