把下面的题目因式分解用分组分解法(1)ax^2+ay^2-2axy-ab^2(2)7x^2-3y+xy-21X(3)3a^2+bc-3ac-ab(4)a^2m+bn-an-abm(5)x^2-a^@-2x-2a(6)4a^2+12ab+9b^2-25(7)ax^2-4xy+y^2-a^2(8)1-m^2-n^2+2mn第7题4X^2-4XY+Y^2-A^2

Question

把下面的题目因式分解
用分组分解法
(1)ax^2+ay^2-2axy-ab^2(2)7x^2-3y+xy-21X
(3)3a^2+bc-3ac-ab(4)a^2m+bn-an-abm
(5)x^2-a^@-2x-2a(6)4a^2+12ab+9b^2-25
(7)ax^2-4xy+y^2-a^2(8)1-m^2-n^2+2mn
第7题4X^2-4XY+Y^2-A^2

Answer 1

(1)ax^2+ay^2-2axy-ab^2=a(x^2+y^2-2xy-b^2)=a[(x-y)^2-b^2)=a(x-y+b)(x-y-b)(2)7x^2-3y+xy-21x=(7x^2-21x)+(xy-3y)=7x(x-3)+y(x-3)=(x-3)(7x+y) (3)3a^2+bc-3ac-ab=(3a^2-3ac)+(bc-ab)=3a(a-c)-b(a-c)=(a-c)(3a-b)(...