Existence and Uniqueness of a Solution
If $$f(x)$$ is continuous on $$[a,b]$$, strictly monotonic on $$[a,b]$$, and:
$$k\in[f(a),f(b)]$$
then:
$$f(x)=k$$
has exactly one solution in $$[a,b]$$.
Usage
- Used to prove that an equation has exactly one solution in a specified interval.