Junior high school mathematics function is nothing more than linear function, quadratic function, inverse proportional function, inverse proportional function is relatively simple. In the senior high school entrance examination, the emphasis is generally on the linear function and quadratic function, and the inverse proportional function is generally combined with the other two functions or geometry to understand the moving point problem. Linear function: in fact, it is two propaganda. Y=kx, y=kx+b is a simple proportional function. Needless to say, linear functions should consider increase or decrease. When k is greater than 0 and b is greater than 0, the function passes through quadrant123; K is greater than zero, and B is less than zero, passing through quadrant124; K is less than zero, B is less than zero, it passes through 234 quadrants, K is greater than zero, B is less than zero, it passes through 134 quadrants. Quadratic function has general formula, intersection point and vertex. There is everything in the book, and the main consideration is increase or decrease. Inverse proportional function should be discussed in quadrant. There are too many, you should learn to summarize in the process of doing the problem. The problem of function is generally a set of formulas, but the most important thing is to pay attention to calculation and details, consider quadrants and increase and decrease. Think more ~!