Question

初一：因式分解：ab+b²+a-b-2

ab+b²+a-b-2 2.a²-b²+2b-1
3.x^7-2x^6y+x^5y^2 4.a²-ab+2bc-4c²

Answer 1

1、ab+b²+a-b-2
=ab+a+(b²-b-2)
=a(b+1)+(b-2)(b+1)
=(a+b-2)(b+1)

2、a²-b²+2b-1
=a²-(b²-2b+1)
=a²-(b-1)²
=(a+b-1)(a-b+1)

3、x^7-2x^6y+x^5y^2
=x^5·(x²-2xy+y²)
=x^5·(x-y)²

4、a²-ab+2bc-4c²
=a²-4c²-(ab-2bc)
=(a+2c)(a-2c)-b(a-2c)
=(a+2c-b)(a-2c)

Answer 2

1. (b+a-2)(b+1)

2. (a+b-1)(a-b+1)

3. x^5(x-y)^2

4. (a+2c)(a-b-2c)
   

Answer 3

(b+1)(a+b-2)