discrete_mathematics_with_a.../chapter_5/test_yourself.md
2026-06-20 20:41:37 -07:00

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**Test Yourself**
Page 296
1. The notation $\sum_{k = m}^{n}{a_k}$ is read "_____."
The summation from $k$ equals $m$ to $n$ of $a$ sub $k$.
2. The expanded form of $\sum_{k = m}^{n}{a_k}$ is _____.
$$ a_m + a_{m + 1} + a_{m + 2} + \dots + a_n $$
3. The value of $a_1 + a_2 + a_3 + \dots + a_n$ when $n = 2$ is "_____."
$$ a_1 + a_2 $$
4. The notation $\prod_{k = m}^{n}{a_k}$ is read "_____."
The product from $k$ equals $m$ to $n$ of $a$ sub $k$.
5. If $n$ is a positive integer, then $n! =$ _____.
$$ n \cdot (n - 1) \dots \cdot 3 \cdot 2 \cdot 1 $$
6. $\sum_{k = m}^{n}{a_k} + c\sum_{k = m}^{n}{b_k} =$ _____.
$$ \sum_{k = m}^{n}{a_k + cb_k} $$
7. $\left(\prod_{k = m}^{n}{a_k}\right)\left(\prod_{k = m}^{n}{b_k}\right) =$
_____.
$$ \prod_{k = m}^{n}{a_kb_k} $$
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**Test Yourself**
Page 309
1. Mathematical induction is a method for proving that a property defined for
integers $n$ is true for all values of $n$ that are _____.
greater than or equal to some initial value.
2. Let $P(n)$ be a property defined for integers $n$ and consider constructing a
proof by mathematical induction for the statement "P(n) is true for all
$n \geq a$."
a. In the basis step one must show _____.
that $P(a)$ is true.
b. In the inductive step one supposes that _____ for a particular but
arbitrarily chosen value of an integer $k \geq a$. This supposition is called
the _____. One then has to show that _____.
$P(k)$ is true; inductive hypothesis; $P(k + 1)$ is true.