Exercise · ZW-EUCLID-S-LEMMA-006 · ★★☆ Intermediate
If \(7 \mid 12x\), what can you conclude about \(x\)?
Choose one option.
Show answer
- D. \(7 \mid x\)
Explanation
Since 7 is prime and divides \(12\cdot x\), and 7 does not divide 12, the lemma implies 7 divides \(x\). The other options do not follow from the hypothesis.
Review the concept: Euclid's lemma
If a prime \(p\) divides the product \(ab\), then \(p\) divides \(a\) or \(b\). It is the key property that distinguishes primes from composite numbers.
\[p \mid ab \Rightarrow p \mid a \ \lor\ p \mid b\]
More practice problems: euclid's lemma
- ZW-EUCLID-S-LEMMA-001 If p is prime and p | ab, what can you conclude?
- ZW-EUCLID-S-LEMMA-002 Does Euclid's lemma require p to be prime?
- ZW-EUCLID-S-LEMMA-003 Which is the correct statement of Euclid's lemma?
- ZW-EUCLID-S-LEMMA-004 If p is prime and p | 35, which value can p take?
- ZW-EUCLID-S-LEMMA-005 Which statement about a prime p that does not divide a is true?
- ZW-EUCLID-S-LEMMA-007 If 11 | ab and 11 nmid a, what happens to b?
- ZW-EUCLID-S-LEMMA-008 If p is prime and p | a^2, what follows?
- ZW-EUCLID-S-LEMMA-009 If p is prime and p | abc with p nmid a and p nmid b, what follows?