Mathematical fixed value can be aimed at some situations, we can say that constant is fixed value, but we can't say that fixed value is constant. For example, in one question, A is a fixed value or a/b is a fixed value, and in another question, it is not a fixed value unless the topic is specified, but the constant is always a fixed value.

That is, in a certain writing situation, the numerical value changes, but a certain value remains unchanged, which is a fixed value, such as AX+C = B. Assuming that a c is inconvenient to change anyway, then B is a fixed value.

"Fixed value" is a definite value, which is relative to "variable". Fixed value means that the number you work out is fixed, that's all! For example: 12 is a fixed value, and 28 is a fixed value, because they will not change; But x is a variable, and its value will change.