If (x/y)+(y/x)=-1, then x^3-y^3= ?

• x^2+y^2=(-xy)
  x^3-y^3=(x-y)(x^2+y^2+xy)
  so, =(x-y) (-xy+xy)
  =(x-y)* 0
  =0
• 12 years agoHelpfull: Yes(3) No(0)
• formula for a^3-b^3=(a-b)(a^2+b^2+ab)
  same for
  x^3-y^3=(x-y)(x^2+xy+y^2)
  take common xy on R.H.S
  x^3-y^3=(x-y)xy((x/y)+1+(y/x))................(1)
  but given in question is that (x/y)+(y/x)=-1 (given)
  so put this value in eq(1),we get
  x^3-y^3=(x-y)xy(-1+1)
  =0
  so x^3-Y^3=0,If (x/y)+(y/x)=-1(ans)
  
• 12 years agoHelpfull: Yes(2) No(2)
• Formula is x^3-y^3 = (x-y)(x^2+xy+y^2)
  = xy(x-y)((x/y)-1+(y/x))
  =xy(x-y)(0)(bcz putting value given in question)
  =0
• 12 years agoHelpfull: Yes(2) No(0)