Exercise · ZW-COSET-003 · ★☆☆ Basic
In \((\mathbb{Z},+)\) let \(H=5\mathbb{Z}\). Which coset equals \(17+H\)?
Choose one option.
Show answer
- A. \(2+H\)
Explanation
Two cosets \(a+H\) and \(b+H\) are equal when \(b-a\in H\). Here \(17-2=15\in5\mathbb{Z}\); for the others the difference is not a multiple of \(5\).
Review the concept: Coset
The left coset of a subgroup \(H\) of a group \(G\) with representative \(a\in G\) is the set of products of \(a\) with the elements of \(H\).
\[aH=\{ah:\ h\in H\}\]
More practice problems: coset
- ZW-COSET-001 Let H=\0,3,6,9\ in (ℤ_12,+). What is the coset 1+H?
- ZW-COSET-002 Let H=\0,4,8\ in (ℤ_12,+). How many distinct cosets does H have?
- ZW-COSET-004 Let H be a subgroup of order 4 of (ℤ_20,+). How many elements does the coset 7+H have?
- ZW-COSET-005 Let H=\0,3,6,9\ in (ℤ_12,+). Which of these elements lies in the same coset as 5?
- ZW-COSET-006 In the multiplicative group ℤ_7^* let H=\1,6\. What is the coset 3H?
- ZW-COSET-007 Two left cosets aH and bH share an element. What follows?
- ZW-COSET-008 Let H=langle 12rangle in (ℤ_36,+). How many distinct cosets are there?
- ZW-COSET-009 In S_3 let H=\e,(1 2)\ and g=(1 3). How are gH and Hg related?