龙江南
幼苗
共回答了18个问题采纳率:83.3% 举报
(1)∵△=b
2 ﹣4ac
=[﹣(3m﹣1)]2﹣4m(2m﹣2),
=(3m﹣1)
2 ﹣8m
2 +8m,
=9m
2 ﹣6m+1﹣8m
2 +8m,
=m
2 +2m+1,=(m+1)
2 ;
∴△=(m+1)
2 ≠0,
∴无论m取任何实数时,方程恒有实数根;
(2)∵一元二次方程mx
2 ﹣(3m﹣1)x+2m﹣2=0的两个实数根分别为x
1 ,x
2 .
|x
1 ﹣x
2 |=2,
∴x
1 +x
2 =﹣
![](https://img.yulucn.com/upload/2/1e/21e923396c55b20898557da72b8adb15_thumb.jpg)
=
![](https://img.yulucn.com/upload/7/fe/7fe5a77c9b4be2ed08c95b3a062f98fe_thumb.jpg)
,x
1 x
2 =
![](https://img.yulucn.com/upload/d/01/d01b1f3f8200a4c176a4053b20a356f3_thumb.jpg)
=
![](https://img.yulucn.com/upload/f/f6/ff611d0b7c0fc537767b7aeb46e71d37_thumb.jpg)
;
∴(x
1 ﹣x
2 )
2 =4,
∴x
1 2 +x
2 2 ﹣2x
1 x
2 =4,
∴x
1 2 +x
2 2 +2x
1 x
2 ﹣4x
1 x
2 =4,
∴(x
1 +x2)
2 ﹣4x
1 x
2 =4,
∴(
![](https://img.yulucn.com/upload/0/63/063f170be04775025f9a290cc6ef5874_thumb.jpg)
)
2 ﹣4×
![](https://img.yulucn.com/upload/8/60/860afc950df001516a43cc2c51f1311b_thumb.jpg)
=4,
∴整理得:﹣3m
2 +2m﹣1=0,
解得:m
1 =1,m
2 =﹣
![](https://img.yulucn.com/upload/a/7d/a7d36b68c63cd0e0469fb8b503e8170e_thumb.jpg)
,
∴一元二次方程mx
2 ﹣(3m﹣1)x+2m﹣2=0的两个实数根分别为x
1 ,x
2 ,
且|x
1 ﹣x
2 |=
![](https://img.yulucn.com/upload/6/97/6971f81a20a069e2ce6b8a349636fbc0_thumb.jpg)
,m的值为1或﹣
![](https://img.yulucn.com/upload/6/1e/61e4895bf267bbb80531cbae20afc8cb_thumb.jpg)
.
1年前
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