That is, the function value can be equal to 0, which is reflected in the image that the function has an intersection with the X axis, and there are several zeros when there are several intersections.

There are several solutions for f(x)=0.

For the continuous function f(x) on [x 1, x2], if the signs of f(x 1) and f(x2) are different, then the zero point of f (x) (the solution of f (x) = 0) is on (x 1, x2).