The two questions of "it's better to have a reason" are actually one question, that is, the understanding of f(x). The understanding of f(x) is actually very simple, that is, the ordinate corresponding to the abscissa!

1.

Function f(x)? About a straight line? x=x0？ The abstract expression of symmetry is

F(x0+x)=f(x0-x), where both sides of the equation are vertical coordinates, that is, the vertical coordinate moving x units from x0 to the right is equal to the vertical coordinate moving the same unit to the left.

The equation is that two vertical coordinates are equal, and the two separation points p 1(x0+x, f(x0+x)) and P2(x0-x, f(x0-x)) are about straight lines.

X=x0 is symmetrical, because of the arbitrariness of X, all points on the whole image are symmetrical about the straight line x=x0;

Central symmetry is similar to axial symmetry, but it is not? However, the coordinates are reversed everywhere. According to the vector, one is to look up and the other is to look down. The abstract expression is: f(x0+x)=? -? f(x0-x)？

(2) Objects that are symmetrical to each other are different, and are expressed abstractly? The formula is f(x0+x)=g(x0-x).

This doesn't make much sense. What is useful is how to find the symmetric curve of f(x) about the straight line x=x0.

Method:

S 1: let the equation be g(x) and let P(x, y) be any point in the image where y=g(x).

S2: Find the corresponding point p of p about the straight line x=x0? ? (2X0-x, y) Then substitute the coordinates of point p' into y=f(x).

The equation you get is what you want. ?