How to judge which quadrant a straight line passes through?

Actually, it's really not difficult. Draw more pictures and sum up the rules by yourself.

It's easy to recite words like upstairs (of course, that's also a way, hehe)

You can usually do this problem like this:

1, first establish a coordinate system in the brain.

2. Determine what this function is.

3. See if the focus of this function and the Y axis is positive, negative or zero.

In this way, it is easy to construct a schematic diagram of this function in your mind, and the rest is to look at the picture and speak.

For example: Y=4X-3

Firstly, he is a increasing function. Secondly, he has a negative focus on the Y axis. So there is only one, three and four quadrants.

Supplement: The above applies to straight lines (that is, linear functions), and a similar method can be used to judge curves. But that depends on whether the opening is up or down, the position of the symmetry axis, the positive and negative poles, the positive and negative focus of the Y axis and so on. You can talk about the problems in detail in the future. I mainly want to tell you how to solve this kind of problem, which is much better than memorizing formulas.

A little personal opinion, I hope it will help you _