若关于x的方程(k2-2k)x2-(6k-4)x+8=0的解都是整数,试求实数k的值.
【答案】
分析:(1)根据k
2-2k=0得出k的值,进而求出x的值;
(2)当k
2-2k≠0进行分析,利用代入消元法求出k的值.
解答:解:(1)当k
2-2k=0,即k=0或k=2,
①若k=0时,原方程化为4x+8=0,即x=-2符合题意;
②若k=2时,原方程化为
-8x+8=0,
则x=1符合题意;
(2)当k
2-2k≠0,即k≠0时,原方程可化为:
(k
2-2k)x
2-(6k-4)x+8=0,
解得x
1=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/0.png)
,x
2=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/1.png)
,将k=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/2.png)
,代入x
2=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/3.png)
得x
1x
2+2x
1-x
2-2=-2,
∴
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/4.png)
或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/5.png)
或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/6.png)
或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/7.png)
∴
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/8.png)
或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/9.png)
或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/10.png)
或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/11.png)
(舍去),
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/12.png)
或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/13.png)
或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/14.png)
,
解得:k=1或-2或
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131103195617112793668/SYS201311031956171127936012_DA/15.png)
,
综上:k的值为1,-2,
点评:此题主要考查了一元二次方程整数根的求法和代入消元法解方程,题目难度不大.