l.c.m & h.c.f of two numbers is 84 & 21 respectively and the ratio of these two numbers is 1:4. Find the greatest no…

• 84.
  
  If nos are x and 4 x, then
  x*4x= 84*21
  x^2=21*21
  x=21
  4x=84
• 13 years agoHelpfull: Yes(8) No(3)
• let the numbers be X,Y
  given that X/Y=1/4 ,by cross multiplying we get 4X=Y------eq(1)
  we know that,
  product of two numbers= product of their H.C.F&L.C.M
  so XY=84*21=1764---------eq(2)
  substitute eq(1) in eq(2)
  4(X^2)=1764
  X^2=441
  so X=21
  substitute X value in eq(1) we get Y=84
  so 84 is the greatest number
  
• 12 years agoHelpfull: Yes(4) No(3)
• we have a formula:
  =>LCM*HCF=Product of 2 numbers
  We are given that 2 numbers are in the ratio 1:4. So let the numbers be x and 4x. Substitute in the above formula to get the value of x.
  =>84*21=x*4x
  Solving the above equation we get the value of x as 21.
  So the two numbers are x and 4x.
  Therefore greatest number is 4x=4*21=84.
  Thank u.
  Hope this is useful
• 9 years agoHelpfull: Yes(2) No(0)
• x*4x=21*84
  4x^2=21*84
  x^2=21*84/4
  x=21
  4(x)=>4(21)=84
  ans is 84
• 5 years agoHelpfull: Yes(0) No(0)
• l.c.m*h.c.f=product of 2 numbers
  84*21=x*y
  x/y=1/4->4x=y
  4x^2=84*21
  x=21
  y=4*21=84
• 4 years agoHelpfull: Yes(0) No(0)