Given the inequalities $n > 2^k - 1$ and $n < 2^{(k+1)}$, express $k$ in terms of $n$ (where $k, n \in\Bbb N$).

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I am quite certain that it will require logarithms and the floor function.

I haven't really attempted this on my own, because I have no idea how to even approach this problem. I have, however, spent a good bit of time thinking about it.

Thanks in advance.

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Is it a fundamental mathematical problem of inequalities? (In my understanding) I think we need to solve a set of inequalities representing the relationship between two natural numbers in expressions. In this problem, we need to express the natural number $k$ as an expression for another natural number $n$ that satisfies both inequalities given. This is a common mathematical problem that can be solved by algebraic operations and mathematical reasoning.

We are given the inequalities $n > 2^{k} - 1$ and $n < 2^{(k+1)}$, where $k$ and n are natural numbers. The problem asks us to express k in terms of n.

We can solve for k by manipulating the inequalities algebraically. First, let's rewrite $2^{(k+1)}$ as $2\times 2^k$:

\begin{aligned} n > 2^k - 1 \\ n < 2 \cdot 2^k \\ \end{aligned}

We can then solve for k by taking logarithms base 2:

\begin{aligned} k < \log_2(n+1) \\ k \geq \log_2 \frac{n}{2} \end{aligned}

Since k is a natural number, we can take the ceiling of the lower bound:

\begin{aligned} k = \left\lceil \log_2 \frac{n}{2} \right\rceil \end{aligned}

where $\lceil x \rceil$ denotes the smallest integer greater than or equal to $x$.

This expression for $k$ satisfies both inequalities, and is the simplest possible expression in terms of $n$.