It's known that the function is negative at and positive at .
To answer this question, we need to use the Intermediate Value Theorem, which states:
If f(x) is a continuous function on [a, b], then for every k between f(a) and f(b), there exists a value c belongs to (a, b) such that f(c) = k.
Therefore, the function hast a least one solution between and because the function is continuous in the closed interval [0,1], and based on the intermediate value theorem, if there exist a value inside this interval, then there's at least one solution there.