Three men A,B,C working together can do a job in 6hours less time than A alone, in 1 hour less time than B aloneand in one half the time needed by c when working alone.Then A and B together can do the job in ?

• 1/a+1/b+1/c=1/x
  1/(x+6)+1/(x+1)+1/(2x)=1/x
  x=2/3
  1/t=1/a+1/b=1/x-1/c=1/2x=3/4
  t=4/3
  
• 10 years agoHelpfull: Yes(3) No(1)
• 1/a+1/b+1/c=1/x
  1/(x+6)+1/(x+1)+1/(2x)=1/x
  (x+1)(2x)+(x+6)(2x)+(x+1)(x+6)/(x+1)(x+6)(2x)=1/x
  5x^2+21x+6/2x^3+14x^2+12x=1/x
  5x^3+21x^2+6x=2x^3+14x^2+12x
  3x^3+7x^2-6x=0
  x(3x^2+7x-3)=0
  x(3x^2+9x-2x-6)=0
  x(3x(x+3)-2(x+3))=0
  x(3x-2)(x+3)=0
  therefore x=0
  x=2/3
  x=-3
  x=2/3 is considered
  1/t=1/a+1/b=1/x-1/c=1/2x=3/4
  t=4/3
  
• 10 years agoHelpfull: Yes(2) No(2)
• 1/a+1/b+1/c=1/x
  1/(x+6)+1/(x+1)+1/(2x)=1/x
  x=2/3
  1/t=1/a+1/b=1/x-1/c=1/2x=3/4
  t=4/3
• 10 years agoHelpfull: Yes(1) No(1)