The LCM of two positive nos is 168 and their product is 504.
what is the difference in their squares?
A. 175 B.216 C.9 D.135

Answer Posted / prasun bose

let the numbers be a and b
so by question---ab=504 the product
and LCM= ab/common factor=168
so common factor=ab/168 =504/168 =3
factors of LCM 168=2,2,2,3,7
so taking 3 on both side,we have
2,2,2and3 is one nunber and the other is
3,and 7 . so the numbers are 24 and 21
now the difference of the square of these nunbers
is a2-b2=(a+b)(a-b)=(24+21)(24-21)=45(3)=135
thus the answer is D

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