The cubic sum-difference formula is specially trained as follows for reference:

I. Cubic sum formula

Cubic sum formulas are sometimes used in mathematical operations. The literal expression of this formula is: the sum of two numbers, multiplied by the difference between their square sum and product, is equal to the cubic sum of these two numbers; The expression is: (a+b)(a? -ab+b？ )=a？ +b？ ;

Quadratic and cubic difference formulas

Cubic difference formula is one of the commonly used formulas in mathematics. Contact this formula of high school mathematics. The complete cubic difference formula and the complete cubic sum formula * * are called complete cubic formulas; Specifically: the sum of squares of two numbers plus the product of two numbers and then multiplied by the difference of two numbers, the product is equal to the cubic difference of two numbers; Expressed by the formula: A3-B3 = (a-b) (A2+AB+B2);

Fourth, the derivation process

1, cubic sum formula: a3+B3 = (a+b) 3-3ab (a+b) = (a+b) [(a+b) 2-3ab] = (a+b) (a2+B2).

2. For the cubic difference formula, in the cubic sum formula "A 3+B 3 = (A+B) (A 2-AB+B 2)", replace "B" with "(-B)": A 3+(-B) 3 = [A+(.

3. Complete cube sum formula (A+B) 3 = (A+B) (A+B) 2 = (A+B) (A2+2AB+B2) = A3+2 (A2) B+A (B2)+(A

4. Complete cubic difference formula: In the complete cubic sum formula "(A+B) 3 = A 3+3 (A 2) B+3A (B 2)+B 3", replace "B" with "(-b)" to get [A+(-B)].