In a sequence of integers, A(n)=A(n-1)-A(n-2),where A(n) is the nth term in the sequence, n is an integer and n>=3, A(1)=1,A(2)=1. Calculate S(1000), where S(1000) is the sum of first 1000 terms.

• sorry i took A(1)=-1,bt given A(1)=1
  dat was wrong
  check it now
  A(1)=1,A(2)=1.
  A(3)=A(2)-A(1) acc to the given formula A(n)=A(n-1)-A(n-2)
  A(3)=1-1=0.
  similarliy,A(4)=A(3)-A(2)=0-1=-1.
  A(5)=A(4)-A(3)=-1-0=-1.
  A(6)=A(5)-A(4)=-1-(-1)=0.
  after 6th term seq is repeating like...1,1,0,-1,-1,0...after every 6 terms
  so the sum of these 6 terms are 1+1+0+(-1)+(-1)+0=0.
  now we have to find sum of 1000 terms...
  sum of first 600 terms is 0...(as consider 1,1,0,-1,-1,0 as one sequence,now consider 166 seq i.e 166*6=996 terms)
  so the sum of first 996 terms is 0...after that 4 terms come i.e 1,1,0,-1
  so the sum of last 4 terms = 1+1+0+(-1)=1.
• 12 years agoHelpfull: Yes(43) No(0)
• a[1]=1
  a[2]=1
  a[3]=a[2]-a[1]=1-1=0
  subsequently series
  1,1,0,-1,-1,0,1,1,0,-1,-1,0...
  1000/6=166.66
  166*6=996
  1000-996=4
  1+1+0+(-1)=1(from series)
  
  answer=1
• 12 years agoHelpfull: Yes(10) No(0)
• A(1)= -1
  A(2)= 1
  A(3)= 2
  A(4)=A(3)-A(2)= 1
  A(5)=A(4)-A(3)= -1
  A(6)=A(5)-A(4)= -2
  A(7)=A(6)-A(5)= -1 =A(1)
  A(8)=A(7)-A(6)= 1 =A(2)
  So,next terms can easily be predicted from the previous steps.
  A(9)=A(3)=2
  A(10)=A(4)= 1
  A(11)=A(5)= -1
  A(12)=A(6)= -2
  A(13)=A(7)=A(1)=-1
  A(14)=A(8)=A(2)=1
  the sum of 1st 6 terms = A(1)+A(2)+A(3)+A(4)+A(5)+A(6)=-1+1+2+1-1-2=0
  Now, 1000 = 6*166 + 4
  So, S(1000) = 166*0 +{A(1)+A(2)+A(3)+A(4)} = 0+ {-1+1+2+1} = 3
  dats y i think 3 will b d correct ans
• 12 years agoHelpfull: Yes(3) No(4)
• @mrudula yup i knw an z nt der...dis z a tcs openseesame ques...n dis the correct method...in dat dey r showing ans z 3..i dnt knw hw 3 ll cum,if u knw den tel us
• 12 years agoHelpfull: Yes(2) No(0)
• ans will b 3
• 12 years agoHelpfull: Yes(1) No(5)
• the correct answer to this question is 3 as per the open seesame test but i dnt knw hw they got this answer.
• 12 years agoHelpfull: Yes(0) No(1)
• plz send me tcs new pattern questionson on egra.subha@gmail.com
  
• 12 years agoHelpfull: Yes(0) No(0)
• hai sanjana one is not der in the options pls check and post the correct one
• 12 years agoHelpfull: Yes(0) No(0)