frank proposes the following problem in the class.
If a = 1 + 3 + 5 + 7 + .. + 31
and b = 2 + 4 + 6 + 8 + ... + 32
then the value of (a - b)2 is
1024
256
225
961

• answer is 256..
  value of a can be find out as (1+2+3+--31)-(2+4+6---30)=256
  and b can be find out as 2(1+2+--16)= 272
  (a-b)^2= a^2 + b^2 -2ab= 256
• 11 years agoHelpfull: Yes(19) No(0)
• sum of even no. starting with 2 is n^2
  sum of odd no starting with 1 is n*(n+1)
  where n is no of terms
  so a=256 and b=272
  so(a-b)=(-16)^2=256
• 11 years agoHelpfull: Yes(6) No(1)
• ans is 256....
  
• 11 years agoHelpfull: Yes(3) No(4)
• ans is 256 bcoz this is a ap series ans formulae of sum of ap
  sum=n(a+l)/2
  where n=total terms
  a=first term
  l=last term
  (a-b)^2=(256-272)^2=256
• 11 years agoHelpfull: Yes(2) No(0)
• how the ans is 256
• 11 years agoHelpfull: Yes(1) No(0)
• 1-2=-1
  3-4=-1
  
  so like this we get -16 square of it is 256 simple ha ha ha
• 11 years agoHelpfull: Yes(1) No(0)
• a^2+b^2-2*a*b
  a is sum of odd terms.
  b is sum of even terms.
  a=32*8
  b=34*8
  now find a^2 and b^2
• 11 years agoHelpfull: Yes(0) No(2)