The simplest understanding is to put them in front in the form of Hua Song X and the coefficient is positive, then draw three straight lines with the equal sign as the equal sign, and then the area less than is on the left and the area greater than is on the right. Then translate the required straight line and find out the answer.

If you just want the answer, you can try it directly. The answer is often the intersection of three straight lines, and you can get the answer.