解一元二次方程之十字相乘法专项练习题
解一元二次方程十字相乘法专项
练习题
2
(1) a 2-
7a+6=0;(2)8
x
2
2+6x-35=0;
(3)18x 2-21x+5=0;(4)
20
2
-9y-
20y2=0;
2 (5)2x
2+3x+1=0;(6)2
y
2
2+y-6=0;
2 (7)6x 2-13x+6=0;(8)3a 22-7a-
6=0;
2
(9)6x 2-
11x+3=0;
(10)4m 2+8m+3=0;
2
(13)4n 2
+4n - 15=0;
(14)6a
2
2
+a -35=0;
2
(15)5x 2
- 8x -13=0;
(16)4x
2
2
+15x+9=0
;
2
(17)15x 2
+x -2=0;
(18)6y
2
2
+19y+10=0
;
(20)7(x -1) 2+4(x - 1) - 20=0
2
(11)10x 2
- 21x+2=0;
(12)8m
2
2
-22m+15=0;
(19) 2(a+b) 2+(a+b)(a -b) -6(a -b) 2=0 ;
参考答案:(1)(a-6)(a-1) ,(3)(3x-1)(6x-5) ,(5)(x+1)(2x+1) ,(7)(2x-
3)(3x-2) ,(9)(2x-3)(3x-1) ,(11)(x-2)(10x-1) ,(13)(2n+5)(2n-3) ,(15)(x+1)(5x-13) ,(17)(3x-1)(5x=2) ,(19)(3a-b)(5b-a) ,(2)(2x+5)(4x-7) (4)-(4y-5)(5y+4) (6)(y+2)(2y-3) (8)(a-3)(3a+2) (10)(2m+1)(2m+3) (12)(2m-3)(4m-5) (14)(2a+5)(3a-7) (16)(x+3)(4x+3) (18)(2y+5)(3y+2) (20)(x+1)(7x-17)
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