The correspondence rule is the correspondence between the independent variable and the dependent variable of the function, as long as the number is meaningful (of course, the actual problem should be considered)

, mainly including: even root number is greater than 0, denominator is not 0, logarithm real number is greater than 0, base number is greater than 0 and not equal to 1, domain of positive cotangent function, domain of inverse trigonometric function and so on.

Scope:

The evaluation domain is actually the problem of finding the maximum value of a function (without the maximum value, it is infinite). The common methods of finding the maximum value are formula, derivative, using inequality and so on.

It is discussed that the type of function is related to the monotonicity of function.

Algebraic expression function: 1 direct generation, quadratic vertex, cubic derivative.

Fractional function: using inequalities (such as mean inequality, x+1/x >; = 2√x*√ 1/x =2) or derivative.

Trigonometric function: each function has its own characteristics and is different (sine and cosine function is [- 1, 1], and positive cotangent function is r).

Refers to logarithmic function: combined with its monotonicity, it is divided into a >；; 0 and 0

(In the whole domain, the range: exponential function: (0, +∞), logarithm.

Function: r, if it is not in the whole field, use the monotonicity of the function to find the maximum and minimum)

Power function: see/view/view/331644.htm.

Inverse trigonometric function: similar to trigonometric function

Two thirds of y=x is a power function,

Domain: it is changed to (x) under the root sign of cubic x) 2, so its domain is R.

Range: (x under the root sign of the third degree) 2 > = 0, so the range is: [0, +∞)