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【搜题】十字相乘的因式分解题目!

来源:学生作业帮 编辑:拍题作业网作业帮 分类:数学作业 时间:2024/05/19 20:26:57
【搜题】十字相乘的因式分解题目!
请给我初一十字相乘的因式分解题目30题以上、、谢谢、、、
最好有答案、、不需要过程、、、
练习
把下列各式分解因式:
1.x4-15x2+26; 2.(x+y) 2-(x+y)-2;
3.y4-26y2+25; 4.(a-b) 2+6(b-a)+5;
5.(x2-2x)2-7(x2-2x)-8; 6.x2-2xy-8y2;
7.x2+(a+b)x+ab; 8.x4-7x2y2+6y4;

答案:
1.(x2-13)(x2-2); 2.(x+y+1)(x+y-2);
3.(y+5)(y-5)(y+1)(y-1); 4.(a-b-1)(a-b-5);
5.(x-4)(x+2)(x-1) 2; 6.(x+2y)(x-4y);
7.(x+a)(x+b); 8.(x+y)(x-y)(x2-6y2);

小结
把下列各式分解因式:
1.(1)x4+7x2-18; (2)x6+8x3+15;
(3)m2x2-8mx+12; (4)x2y2-7xy+10;
2.(1)x2-7xy+12y2; (2)a2+2ab-15b2;
(3)m2+4mn-12n2; (4)p2+9pq+18q2.
3.(1)(m+n) 2-(m+n)-30; (2)(x-y) 2-3(x-y)-40;
(3)(2m+n) 2-4r(2m+n)+3r2; (4)(a-b) 2-12(a-b)-45.
4.(1)(x2-4x) 2-(x2-4x)-20; (2)(a2+5a+3)(a2+5a-2)-6.
答案:
1.(1)(x2-2)(x2+9); (2)(x2+3)(x3+5);
(3)(mx-2)(mx-6); (4)(xy-2)(xy-5).
2.(1)(x-3y)(x-4y); (2)(a+5b)(a-3b);
(3)(m-2n)(m+6n); (4)(p+3q)(p+6q).
3.(1)(m+n-6)(m+n+5); (2)(x-y+5)(x-y-8);
(3)(2m+n-r)(2m+n-3r); (4)(a-b-15)(a-b+3).
4.(1)(x+1)(x-5)(x-2) 2;
(2) (a2+5a+3)(a2+5a-4)-6
=[(a2+5a)+3][(a2+5a)-2]-6
=(a2+5a) 2+(a2+5a)-12
=(a2+5a+4)(a2+5a-3)
=(a+1)(a+4))(a2+5a-3).
可以吗?