If we already know that the function f(x) has a zero point in the interval (a, b), then the further question is, how to find this zero point?

An intuitive idea is that if we can narrow the range of zero as much as possible, then we can get an approximate value of zero with certain accuracy. For convenience, the range of zero point is gradually reduced by the method of "taking the midpoint".

After repeating the same steps a finite number of times, we can take any point in the interval where the obtained zero is located as the approximation of the function zero. In particular, we can take the endpoint of the interval as the approximation of the zero.

For the function y=f(x) which is continuous in the interval [a, b] and f (a) f (b) < 0, the method of dividing the interval where the zero point of the function f(x) is located into two parts, making the two endpoints of the interval gradually approach the zero point, and then finding the approximate value of the zero point is called dichotomy.

Here we need f (a) f (b) < 0, that is, the symbol of f(x) near zero, which geometrically passes through the X axis (intersection point).

The zero point that cannot be solved by dichotomy belongs to f (a) f (b) >: 0 has the same sign as the zero point of f(x) and is geometrically tangent to the X axis.

Back to the topic, the zero tangent point is the point between 1.9 and 2.3, which is C.