Question

The lcm of two numbers x and y is 720 and the lcm of numbers 12x and 5y is also 720 find y

Answer 1

1st number =12x

2nd number =5y

L.C.M. of 12x and 12y =60 x.y , Acordingly:-

60x.y=720

x.y =12…………..(1)

x×y =12×1 if x=12 , y=1 numbers are 144 , 5.

L.C.M. of 144 and 5 =720 (true)

x×y=6×2 if x=6 , y= 2 ,numbers are 72 ,10 .

L.C.M. of 72 and 10 =360 (false)

x×y=4×3 if x=4 ,y =3 ,numbers are 48 ,15.

L.C.M.of 48 and 15 = 240. (false).

x×y=3×4 if x=3 ,y=4 numbers are 36 ,20

L.C.M. of 36 and20 =180 (false).

x×y=2×6 if x=2 ,y=6 numbers are 24 ,30

L.C.M.of 24 and 30 = 120 (false).

x×y=1×12 if x =1 , y =12 numbers are 12 , 60

L.C.M.of 12 and 60 =60 (false).

Only 144 and 5 are required numbers. Answer.