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| Question 26590:  Let (Tn) = (1, 1, 2, 3, 5, 8, 13, 21, 34, 55, . . .) be the Fibonacci sequence defined by
 T1 = T2 = 1, Tn = T(n−1) + T(n−2) if n > 2.
 Show that the following hold for n that is greator or equal to 1.
 T2+T3+...+T(2n-1)=T(2n)
 Answer by venugopalramana(3286)
      (Show Source): 
You can put this solution on YOUR website! Let (Tn) = (1, 1, 2, 3, 5, 8, 13, 21, 34, 55, . . .) be the Fibonacci sequence defined by T1 = T2 = 1, Tn = T(n−1) + T(n−2) if n > 2.
 Show that the following hold for n that is greator or equal to 1.
 T2+T3+...+T(2n-1)=T(2n)
 WE HAVE
 T1=1
 T2=1.......OR.......................................T2-T1=0
 T3=T2+T1............................................T3-T2=T1
 T4=T3+T2............................................T4-T3=T2
 T5=T4+T3............................................T5-T4=T3
 ...........................................................................
 .............................................................................
 T2N=T(2N-1)+T(2N-2)...........................T2N-T(2N-1)=T(2N-2)
 ADDING ALL ABOVE ,WE FIND ON THE LHS ,ALL EXCEPT T2N AND -T1 CANCEL EACH OTHER.SO WE GET
 T2N-T1=T1+T2+T3+.........+T(2N-2)...OR......
 T2N=T1+{T1+T2+T3+........T(2N-2)}
 T2N=1+{T1+T2+T3+........T(2N-2)}...THIS IS THE ANSWER.YOUR QUESTION IS NOT CORRECT YOU CAN CHECK AS BELOW...WE HAVE
 T1=1..=	1
 T2=1..=	1
 T3=1+1=	2
 T4=2+1=	3
 T5=3+2=	5
 T6=5+3=	8
 T7=8+5=	13
 T8=13+8=21	..SO T2N=T8=1+T1+T2+T3+T4+T5+T6=1+(1+1+2+3+5+8)=21..THAT IS
 .........................T8=1+{T1+T2+T3+........T(8-2)}...AND NOT
 T2N=T2+T3+...+T(2n-1) WHICH GIVES US T8=T2+T3+T4+T5+T6+T(8-1)
 =1+2+3+5+8+13=32...WHICH IS NOT CORRECT AS T8=21
 FURTHER FIBONACCI SEQUENCE IS
 0,1,1,2,3,5,8......ETC...WITH THE PROPERTY THAT TN=T(N-1)+T(N-2)...AND T1=0 AND T2=1.
 
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