Eighth grade math problem! And please write down the detailed process on paper?
The answer is 5. The reverse use of the complete square difference formula partially converts the simple form of the required value into the complete square difference form (A-B) 2+2ab+7, and the result can be calculated by substituting A and B. In the settlement process, the formula A2-B2 = (A-b)x(a-B) is flexibly used, which can be used in reverse.