Hint for 2.18(iii). Use the following lemma I proved in class:
Lemma. $\forall k\in \mathbb{N}$, $k^2+k$ is even.
Homework 8 - Due: Feb 15; Final Due Date: 27 Feb
2.23, 2.27.
Homework 9 - Due: Feb 16; Final Due Date: 29 Feb
2.33.
Hint for 2.33. Consider the set $C:=\{a-b+1:a\in A\}$. Show that $C$ is a nonempty subset of $\mathbb{N}$. Then use the Well-Ordering Principle (Theorem 2.32) and use the smallest element of $C$ to find the smallest element of $A$.
Homework 10 - Due: Feb 22; Final Due Date: 2 Mar
4.5.
Homework 11 - Due: Feb 23; Final Due Date: 7 Mar
4.7(i).
Homework 12 - Due: Feb 27; Final Due Date: 8 Mar
4.13, 4.15(iii), 4.16(ii), 4.17.
Binomial Theorem Practice (You do not need to turn this in)
Check out the Multinomial Theorem. The coefficients of the multinomial expansion can be realized by a generalized version of Pascal's Triangle to higher dimensions, called Pascal's simplex.
Homework 13 - Due: Mar 2; Final Due Date: 15 Mar
4.30.
Homework 14 - Due: Mar 5; Final Due Date: 16 Mar
5.3(iii), 5.7.
Homework 15 - Due: Mar 7; Final Due Date: 19 Mar
5.15.
Hint for 5.15. Use the following:
$x\in A\cap B$ $\iff$ $x\in A$ and $x\in B$.
$x\in (A\cap B)^\text{c}$ $\iff$ $x\notin A\cap B$ $\iff$ $x\notin A$ or $x\notin B$. (Notice that this is the negation of: $x\in A$ and $x\in B$.)
$x\in A\cup B$ $\iff$ $x\in A$ or $x\in B$.
$x\in (A\cup B)^\text{c}$ $\iff$ $x\notin A\cup B$ $\iff$ $x\notin A$ and $x\notin B$. (Notice that this is the negation of: $x\in A$ or $x\in B$.)
Homework 16 - Due: Mar 8; Final Due Date: 21 Mar
5.20.
Homework 17 - Due: Mar 12; Final Due Date: 23 Mar
6.5.
Hint for 6.5. If $p$ and $q$ are statements, then to prove "$p$ OR $q$" you may use either of the following methods:
Method 1: suppose $p$ is false, and show $q$ must be true.
Method 2: suppose $q$ is false, and show $p$ must be true.
N.B. You do not need to use both methods (just pick one!)! Why do these methods work? Also, what are some other methods to prove "$p$ OR $q$"?
Homework 18 - Due: Mar 16; 1st Version Final Due Date: Mar 21; Rewrite Final Due Date: 29 Mar
6.15.
Homework 19 - Due: Mar 19; 1st Version Final Due Date: Mar 23; Rewrite Final Due Date: 30 Mar
6.20.
Homework 20 - Due: Mar 26; 1st Version Final Due Date: Mar 29; Rewrite Final Due Date: 13 April
6.25.
Homework 21 - Due: Mar 29; 1st Version Final Due Date: April 12; Rewrite Final Due Date: 18 April
6.32, 6.35.
Homework 22 - Due: April 12; 1st Version Final Due Date: April 16; Rewrite Final Due Date: 20 April
8.6, 8.40(ii), 8.43.
Homework 23 - Due: April 12; 1st Version Final Due Date: April 18; Rewrite Final Due Date: 25 April
8.50.
Homework 24 - Due: April 18; 1st Version Final Due Date: April 20; Rewrite Final Due Date: 30 April
9.11, 9.15.
Homework 25 - Due: April 19; 1st Version Final Due Date: April 23; Rewrite Final Due Date: 2 May
9.18.
Homework 26 - Due: April 20; 1st Version Final Due Date: April 26; Rewrite Final Due Date: 3 May
10.7.
Homework 27 - Due: April 23; 1st Version Final Due Date: April 27; Rewrite Final Due Date: 4 May
10.9.
Homework 28 - Due: April 25; 1st Version Final Due Date: April 30; Rewrite Final Due Date: 7 May
10.17.
Homework 29 - Due: April 26; 1st Version Final Due Date: May 2; Rewrite Final Due Date: 9 May
10.21(i), 10.23(iii).
Homework 30 - Due: April 27; 1st Version Final Due Date: May 3; Rewrite Final Due Date: 10 May
10.27, 10.28, 11.2, 11.6.
Homework 31 - Due: April 30; 1st Version Final Due Date: May 4; Rewrite Final Due Date: 11 May
11.12.
Homework 32 - Due: May 2; 1st Version Final Due Date: May 4; Rewrite Final Due Date: 11 May
11.17.
Homework 33 - Due: May 3; 1st Version Final Due Date: May 9; Rewrite Final Due Date: 11 May
11.25.
Homework 34 - Due: May 7; 1st Version Final Due Date: May 10; Rewrite Final Due Date: 11 May