Hello, landlord! ! The root-penetrating method of number axis, also known as "using number axis", is the first step: the term of inequality is shifted through many properties of inequality, so that the right side is 0 and the factor is decomposed. (Note: Make sure that the coefficient before x is positive) For example, put x3-2x2-x+2 >; 0 to (x-2)(x- 1)(x+ 1)>0 Step 2: replace the unequal sign with an equal sign and solve all the roots. For example, the root of (x-2)(x- 1)(x+ 1)=0 is: x 1=2, x2= 1, x3=- 1 Step 3: From left to right on the number axis. For example:-1 1 2 Step 3: Draw a line through the roots: Draw a line from the upper right to the lower left of the rightmost root based on the number axis, and then go up through the second rightmost root and pass through each root one by one. Step 4: Observe the inequality. If the inequality is ">", take the range above the number axis and within the root line; If the sign is not equal to "",take the range above the number axis and within the root line. Namely:-12. It should be noted that every x coefficient is positive before entering the root, otherwise the negative sign should be extracted first, and the direction of the corresponding inequality sign should be changed before entering the root. For example, (2-x) (x-1) (x+1); 0 to (x-2)(x- 1)(x+ 1)>0 Step 2: replace the unequal sign with an equal sign and solve all the roots. For example, the root of (x-2)(x- 1)(x+ 1)=0 is: x 1=2, x2= 1, x3=- 1 Step 3: From left to right on the number axis. For example:-1 1 2 Step 3: Draw a line through the roots: Draw a line from the upper right to the lower left of the rightmost root based on the number axis, and then go up through the second right heel and pass through each root one by one. Step 4: Observe the inequality. If the inequality is ">", take the range above the number axis and within the heel line; If the sign is not equal to "",take the range above the number axis and within the following line. Namely:-12. Odd and even numbers are opaque, that is, if two solutions are the same number, the number should be penetrated by two numbers, such as (x- 1) 2 = 0, and both solutions are 1, so don't penetrate 1 when penetrating.