If a2+b2-4(a+b)= -8,then the value of (a-b) is:
A. 4
B. 0
C. 2
D. 8

• The answer is b.0 consider a=2 and b=2 it satisfy the expression and match the option as well
• 5 years agoHelpfull: Yes(21) No(28)
• let (a-b)^2 = 0
  a^2+b^2-2ab = 0//eq(1)
  from given statement a^2+b^2=4(a+b)-8
  4(a+b)-8-2ab = 0
  (a-2) (4-2b) = 0
  a=2,b=2
  therefore a-b=2-2=0
• 5 years agoHelpfull: Yes(10) No(8)
• a^2 +b^2 - 4(a+b)=-8
  a^2+b^2 +2ab -2ab -4(a+b)=-8
  (a-b)^2 +2ab -4a -4b +8=0
  (a-b)^2 +2a(b-2) -4(b-2)=0
  (a-b)^2 +(2a-4)(b-2)=0
  (a-b)^2 = -2(a-2)(b-2) // LHS is positive no. so should be RHS and a perfect square(options are integral)
  question is incomplete apparently, there must have been an assumption on value a & b can take.
• 5 years agoHelpfull: Yes(5) No(4)
• a+b=4;
  here a=3 and b=1;
  then(a-b)=(3-1)=2
  (a-b)=2.
• 5 years agoHelpfull: Yes(4) No(20)
• a2+b2=2ab
  2ab=a(a+b)+8
  finally,
  a=2,b=2
  (a-b)=0
• 5 years agoHelpfull: Yes(2) No(3)
• assume that a=2 and b=2 then only the equation will be satisfied
  hence a-b = 2-2 =0
• 5 years agoHelpfull: Yes(2) No(3)
• lets assume a=2 and b=2
  4+4-16=-8
  then 2-2=0
• 5 years agoHelpfull: Yes(2) No(3)
• (a-b)(a+b)=a^2-b^2
• 4 years agoHelpfull: Yes(0) No(0)