1.

A positive integer n is of the form n = 2 alpha 3 beta , where alpha, beta ge 1. If n has 12 positive divisors and 2n has 15 positive divisors then number of positive divisors of 6n is

Answer»

21
20
16
15

Solution :`(alpha+1)(BETA+1)=12`
`(alpha+2)(beta+1)=15`
`implies beta = 2, alpha = 3`
Now `(alpha+2)(beta+2) = 5xx4 = 20`.


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