函数总结大全（Function summing up）.docVIP

函数总结大全（Function summing up） f9b A function I. definition and definition: The independent variable x and dependent variable y have the following relation: Y = kx + b So lets say that y is a function of x. And in particular, when b is equal to 0, y is a positive proportional function of x. That is, y = kx (k is constant, k is not 0) Ii. Properties of a function: 1. The change in y is proportional to the change in x, and the ratio is k That is, y = kx + b (k is any real number that is not zero) When x is equal to 0, b is the intercept of the function on the Y-axis. Iii. Image and properties of a function: 1. Practice and graphics: through the following three steps (1) list; (2) stroke; (3) wire, you can make a graph of a function -- a line. So, the graph of a function is just two points, and its a straight line. (usually find the intersection between function image and X-axis and Y-axis) 2. Nature: (1) any point P (x, y) on a function satisfies the equation: y = kx + b. (2) the coordinates of a function with the Y-axis are always (0, b), and the X-axis is always given to (-b/k, 0) the graph of the positive proportional function is always over the origin. 3. K, b and function image quadrant: When k, , 0, the line is going through one or three quadrants, and y increases with x; When k is less than 0, the line will decrease with the increase of x in the second and fourth quadrant. When b, , 0, the line is going to go through one, two. When b is equal to 0, the line goes through the origin When b is less than 0, the line will go through three or four quadrants. In particular, when b is equal to O, the line is represented by the graph of the positive proportional function through the origin O (0, 0). At this point, when k 0, the line is only going through one or three quadrants; When k is less than 0, the line only passes through two or four quadrants. 4, determine the expression of a function: So I have point A (x1, y1); B (x2, y2), please determine the expression of A fu