Elitmus
Exam
Numerical Ability
LCM and HCF
The difference of two numbers is 14.their lcm and hcf are 441 and 7.find the numbers.
a, 21,35
b, 35,49
c, 49,63
d, 63,77
Read Solution (Total 29)
-
- c) 49,63
Since their HCFs are 7, numbers are divisible by 7 and are of the form 7x and 7y
Difference = 14
=> 7x - 7y = 14
=> x - y = 2
product of numbers = product of their hcf and lcm
=> 7x * 7y = 441 * 7
=> x * y = 63
Now, we have
x * y = 63 , x - y = 2
=>x = 9 , y = 7
The numbers are 7x and 7y
=> 63 and 49
=> option c - 10 years agoHelpfull: Yes(46) No(0)
- since n1*n2=hcf*lcm
apply this formula nd check it from solution
hcf*lcm =441*7=------( first digit is 7)so check only 49,63 after multiplying gives frist digit 7. - 10 years agoHelpfull: Yes(13) No(0)
- try to solve through option see 441*7 its first digit is 7 and in option by checking all only 49*63 has 7 at its first digit so ans is 49,63.
- 9 years agoHelpfull: Yes(8) No(0)
- Let 1st no=x,2nd no=y,
A/c to qustn,x-y=14
x=14+y
we know,
HCF*LCM=n1*n2
7*441=x*y
3087=(14+y)*y
3087=14y+y^2
y^2+14y-3087=0
y^2+63y-49y-3087=0
y(y+63) -49(y+63)=0
(y-49) (y+63)=0
so,y=49,then x=y+14=49+49=63
Hence,nos are 49 and 63. - 9 years agoHelpfull: Yes(3) No(0)
- 49,63 USING
7A*7B=441
7A-7B=2 - 10 years agoHelpfull: Yes(2) No(0)
- product of two nos=LCM*HCF
therefore 441*7=49*63 through option - 10 years agoHelpfull: Yes(1) No(0)
- easy trick...check by options...
a) LCM(21,35)= 105 & HCF(21,35)=7
B) LCM(35,49)=245 & HCF(35,49)=7
C)LCM(49,63)=441 & HCF(49,63)=7
D)LCM(63,77)=693 & HCF(63,77)=7
So the answer is c. - 9 years agoHelpfull: Yes(1) No(1)
- answer is part c.
lcm*hcf= no.
441*7=7*7*7*9=49,63
63-49=14
- 9 years agoHelpfull: Yes(1) No(0)
- step 1:- product of two numbers = LCM of numbers * HCF of numbers
= 441 * 7
= 3087
step 2:- take a look which pairs from option gives 3087 on multiplying
option (c) = 49 * 63 = 3087 (also holds the property that HCF of numbers divides it fully i.e 7 divides 49 and 63 completely).
step 3:- option (c) is the correct choice.
- 8 years agoHelpfull: Yes(1) No(0)
- The LCM is to be checked since the HCF and the difference is satisfied in all the other options.
Answer. c. 49,63 - 10 years agoHelpfull: Yes(0) No(0)
- 441/7= 63
441*7/63=441/9= 47 - 10 years agoHelpfull: Yes(0) No(0)
- Ans is c
x^2-(14)x-3087=0
i will form bcoz lcm*hcf =product of numbers - 10 years agoHelpfull: Yes(0) No(0)
- by checking options we get lcm 441 only for 49 nd 63
- 10 years agoHelpfull: Yes(0) No(0)
- are this level questions comes in elitmus?
- 9 years agoHelpfull: Yes(0) No(0)
- by the help of option u can answer.......answer is C
- 9 years agoHelpfull: Yes(0) No(0)
- option c is the ans.
- 9 years agoHelpfull: Yes(0) No(0)
- (a+b)^2=(a-b)^2+4ab;
(a+b)^2=14^2+4*441*7; (since a*b=lcm*hcf,and a-b=14 given)
a+b=112;..................(i)
and a-b=14;............................(ii)
so add (i) and (ii) and get
a=63;
and b=49; (by putting the value of a in equation (i) get b);
answer - c; - 9 years agoHelpfull: Yes(0) No(0)
- no = hcf*LCM
= 441*7
= 3087
NOW MULTIPLICATIN OF TWON NO EQUALLS TO THAT NO
SO 49*63=3087
ANS-C - 9 years agoHelpfull: Yes(0) No(0)
- let the numbers are x and y
according to question x-y=14
then, x=14+y
so we know x*y=HCF*LCM
(14+y)*y=441*7
y^2+14y-3067=0
y= -63, 49
y=49
x=14+y=63 - 9 years agoHelpfull: Yes(0) No(0)
- Let one number be X. Other number will be 14+X.
Since, HCF and LCM are given
X*(X+14)=HCF*LCM
X^2+14X-144*7=0
Solving the quadratic equation,
X=49
Other number 49+14=63
49,63
- 9 years agoHelpfull: Yes(0) No(0)
- c because a*b=lcm*hcf
- 9 years agoHelpfull: Yes(0) No(0)
(c) 49,63- 9 years agoHelpfull: Yes(0) No(0)
- c)49,63
Let a no is x, then other is x-14.
product of numbers= hcf*lcm.
x*(x-14)=441*7
from solving
u'll find the no. r 49 and 63. - 9 years agoHelpfull: Yes(0) No(0)
- Go through option and check only lcm of those, b'coz difference and hcf of all those options have same, only option- C has lcm as 441 . that's why option C is correct
- 9 years agoHelpfull: Yes(0) No(0)
- (c)=49,63 ans
- 9 years agoHelpfull: Yes(0) No(0)
- option c is right
- 8 years agoHelpfull: Yes(0) No(0)
- c . 49,63
- 6 years agoHelpfull: Yes(0) No(0)
- 49,63
xy*hcf=lcm
xy=63
x-y=14 - 6 years agoHelpfull: Yes(0) No(0)
- c is the answer as we know the hcf of 49 and 63 is 7 and the 441 is the bigger number so try to find a big number whose lcm can give you a number 441 so answer is c
- 5 years agoHelpfull: Yes(0) No(0)
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