For novices of mathematics, do not take those seemingly “naive” problems for granted. Sometimes, the problem at hand is really obvious, but we should still not have frequent logical jumps during the formal rigorous proof, otherwise, we cannot escalate from the qualitative and relatively quantitative realm of engineering, which is often built upon phenomenological metaphors, to the absolutely quantitative realm of mathematics, which requires pure and rigorous reasoning.

On the other hand, the description of the textbook may also have ambiguities which lead to partial or incorrect understanding. Then, the problem should be viewed from different perspectives and approached using different methods, until a most mathematically reasonable and meaningful version is obtained. Here, the said “mathematically reasonable and meaningful” suggests the statement or proposition should neither be too general, which says something absolutely correct but has no practical value or contributes nothing to our knowledge, nor be too narrow, which is only applicable to a quite limited number of specific cases.

Anyway, no matter which of the above two cases a mathematics beginner has met, it is always suggested to follow the route of fastidiousness and rigorousness, which is not at all targeted for satisfying the teacher’s requirements. Try to learn being honest and humble in front of truth and rationality.