154 = 11 × 14 = (?11) × (?14). In the former case x = 11 and 12 × 13 = 156. In the latter case x = ?14
and (?13) × (?12) = 156.
A2. Let v, w, x, y, and z be five distinct integers such that 45 = v × w × x × y × z. What is the sum of the integers?
Solution: The answer is 5 .
Notice that 45 = 3 × 3 × 5. It stands to reason that, to write 45 as a product of five integer factors, each of its prime factors must appear, along with ±1 (we can’t use fractions). Further, to have exactly 5 distinct integers ?3 and ?1 must each appear once. We have 45 = (?1) × 1 × (?3) × 3 × 5. The sum of these five factors is 5.