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Second, choose

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Third, answer questions.

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This part of the extended data mainly examines the knowledge points of rectangular coordinate system:

Draw two axes that are perpendicular to each other and have a common origin on the plane. Where the horizontal axis is the X axis and the vertical axis is the Y axis. In this way, we say that the plane rectangular coordinate system is established on the plane, which is the rectangular coordinate system. It is also divided into the first quadrant, the second quadrant, the third quadrant and the fourth quadrant. Count from the upper right corner and count counterclockwise.

The plane where the coordinate system is located is called the coordinate plane, and the common origin of the two coordinate axes is called the origin of the rectangular coordinate system. X-axis and Y-axis divide the coordinate plane into four quadrants, the upper right quadrant is called the first quadrant, and the other three parts are called the second quadrant, the third quadrant and the fourth quadrant in turn counterclockwise.

Quadrants are bounded by the number axis, and the points on the horizontal axis and the vertical axis do not belong to any quadrant. In the plane rectangular coordinate system, the images of inverse proportional function, positive proportional function, linear function and quadratic function can be drawn according to the point coordinates.

After the establishment of the plane rectangular coordinate system, the plane is divided into four parts by the coordinate axis, which are called the first quadrant, the second quadrant, the third quadrant and the fourth quadrant respectively. (The area of the positive and half shafts of the two shafts is the first quadrant, and the quadrants are arranged in counterclockwise order. )

One-dimensional quadratic equation, when K>0, two branches are located in the first quadrant and the third quadrant respectively, and y decreases with the increase of x in each quadrant; When k < 0, the two branches are located in the second quadrant and the fourth quadrant respectively. In each quadrant, y increases with the increase of X. When the absolute value of X increases infinitely or approaches zero, the two branches with inverse ratio are infinitely close to the X and Y axes, but never intersect with them.