That is, from the ray, from right to left, from top to bottom, passing through in turn, that is, starting from the maximum number, going down from the maximum number, passing through each number in turn, like a wave.

If a value appears twice, it will not be crossed; If it appears three times, it will be crossed (if its value appears odd times, it will not be crossed even times); If the formula is greater than 0, take the top; If it is less than 0, the bottom is taken.

Skills of threading a needle in mathematics;

Step 1: Move the terms of inequality through many properties of inequality, so that the right side is 0 (note: ensure that the coefficient before x is positive).

Step 2: Replace the inequality with the equal sign and solve all the roots.

Step 3: Mark each root in turn from left to right on the number axis.

Step 4: Draw a line through the root: Draw a line from the upper right corner to the lower left corner of the rightmost root based on the number axis, and then pass up through the second right heel, passing through each root one by one.

Step 5: Observe the inequality. If the inequality is ">", take the range above the number axis and within the following line; If the inequality symbol is "