Bunuel
If x, y, and z are integers, is x/(yz) an integer?
(1) y is a factor of x more than once.
(2) All of the prime factors of z are also factors of y.
Here's how I approached it:
Solution required:
x/(yz) is an integer if both y and z are factors of x together, and not just individually
Information Given:
Option 1: y is a factor of x more than once
This implies x = c * y^a where c is some other constant product of the remaining factors of x and a is an integer > 1
BUT
we know nothing about z, so the option is NOT SUFFICIENT
Option 2: All of the prime factors of z are also factors of y.
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An important concept to know here:Consider the number 36. On prime factorization we get:
36 = 2 * 2 * 3 * 3
When we say "ALL PRIME FACTORS" we mean not just the two unique prime factors (2 and 3) but also the repetitions of these unique prime factors.
So, all prime factors = 2,2,3,3
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With this in mind, z is a factor of y
However, we don't know the relationship of x with z or y, hence option 2 is NOT SUFFICIENT
Option 1 and 2 togetherFrom 2, we know that z is a factor of y
From 1, we know that x = c * y^a where a is an integer >1
On combining 1 and 2, we know that yz is a factor of x, therefore x/(yz) is an integer.
Both together are SUFFICIENT.
Answer is C