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by thephoenix » Sun Apr 11, 2010 2:07 am
n^3=450y
450=3^2 * 5^2 *2
to make it a perfect cube we need to multiply it with 3*5*2^2=y(which is nothing but y)
when we insert in the given option we must get an int value
except 1 no option gives us an int value
hence B
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by eaakbari » Sun Apr 11, 2010 3:57 am
Since n and y are integers obviously they are not irrational and hence have perfect cubes

5^2 * 3 ^2 * 2 * y = n^ 3

Now the minimum factors of y needed to complete the cubes are 5 3 and 2^ 2
Hence y = 5*3*2^2* c where c is some constant which is a cube, for eg 27

Now only 1 will render the solution an integer

Hence B
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