If 999x+888y=1332 and 888x+999y=555,then x^2-y^2 is equal to
a)8 b)9 c)5 d)7

• d) 7
  
  999x+888y=1332 -----------eqn 1
  
  888x+999y=555 -----------------eqn 2
  
  1+2 => x+y = 1
  1-2 => x-y = 7
  
  so, x^2-y^2 =(x+y)*(x-y) = 1*7 = 7
  
• 9 years agoHelpfull: Yes(7) No(0)
• add & sub two expressions u will get x+y=1, x-y=7.....x^2-y^2 = (x+y)(x-y) = 1*7 =7
• 7 years agoHelpfull: Yes(0) No(0)