三个二次之间的关系
①抛物线 ![](https://wkrtcs.bdimg.com/rtcs/image?w=93.53&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"93.53","h":"22.47","dataType":"wmf","c":"word/media/image1.png","imgOriW":187,"imgOriH":44})
与轴的相关位置，分为三种情况，这可以由一元二次方程的判别式三种取值情况(，，）来确定．因此，要分二种情况讨论．
②![](https://wkrtcs.bdimg.com/rtcs/image?w=33.07&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"33.07","h":"17.47","dataType":"wmf","c":"word/media/image9.png","imgOriW":66,"imgOriH":34})
可以转化为
分![](https://wkrtcs.bdimg.com/rtcs/image?w=34.93&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"34.93","h":"17.47","dataType":"wmf","c":"word/media/image6.png","imgOriW":69,"imgOriH":34})
，，三种情况，得到一元二次不等式与的解集．
设相应的一元二次方程![](https://wkrtcs.bdimg.com/rtcs/image?w=92.27&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_8","w":"92.27","h":"19.93","dataType":"wmf","c":"word/media/image4.png","imgOriW":184,"imgOriH":39})
的两根为，，则不等式的解的各种情况如下表：(让学生独立完成课本第77页的表格)
|
|
| |
二次函数
|
|
|
|
一元二次方程
| 有两相异实根
| 有两相等实根
| 无实根 |
|
|
| R |
|
|
|
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三个二次之间的关系
![](https://wkrtcs.bdimg.com/rtcs/image?w=34.93&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"34.93","h":"17.47","dataType":"wmf","c":"word/media/image7.png","imgOriW":69,"imgOriH":34})
![](https://wkrtcs.bdimg.com/rtcs/image?w=34.93&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"34.93","h":"17.47","dataType":"wmf","c":"word/media/image8.png","imgOriW":69,"imgOriH":34})
![](https://wkrtcs.bdimg.com/rtcs/image?w=42.40&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"42.40","h":"19.93","dataType":"wmf","c":"word/media/image13.png","imgOriW":84,"imgOriH":39})
![](https://wkrtcs.bdimg.com/rtcs/image?w=99.13&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_11","w":"99.13","h":"116.60","dataType":"png","c":"word/media/image17.png","imgOriW":132,"imgOriH":156})
![](https://wkrtcs.bdimg.com/rtcs/image?w=99.13&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_11","w":"99.13","h":"113.47","dataType":"png","c":"word/media/image18.png","imgOriW":141,"imgOriH":161})
![](https://wkrtcs.bdimg.com/rtcs/image?w=84.80&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_11","w":"84.80","h":"111.60","dataType":"png","c":"word/media/image19.png","imgOriW":123,"imgOriH":162})
![](https://wkrtcs.bdimg.com/rtcs/image?w=92.27&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"92.27","h":"19.93","dataType":"wmf","c":"word/media/image4.png","imgOriW":184,"imgOriH":39})
![](https://wkrtcs.bdimg.com/rtcs/image?w=87.87&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"87.87","h":"21.20","dataType":"wmf","c":"word/media/image20.png","imgOriW":175,"imgOriH":42})
![](https://wkrtcs.bdimg.com/rtcs/image?w=82.93&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"82.93","h":"37.40","dataType":"wmf","c":"word/media/image21.png","imgOriW":165,"imgOriH":74})
![](https://wkrtcs.bdimg.com/rtcs/image?w=92.27&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"92.27","h":"19.93","dataType":"wmf","c":"word/media/image11.png","imgOriW":184,"imgOriH":39})
![](https://wkrtcs.bdimg.com/rtcs/image?w=105.33&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"105.33","h":"25.53","dataType":"wmf","c":"word/media/image22.png","imgOriW":210,"imgOriH":51})
![](https://wkrtcs.bdimg.com/rtcs/image?w=78.53&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"78.53","h":"44.27","dataType":"wmf","c":"word/media/image23.png","imgOriW":157,"imgOriH":88})
![](https://wkrtcs.bdimg.com/rtcs/image?w=92.27&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"92.27","h":"19.93","dataType":"wmf","c":"word/media/image12.png","imgOriW":184,"imgOriH":39})
![](https://wkrtcs.bdimg.com/rtcs/image?w=87.87&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"87.87","h":"25.53","dataType":"wmf","c":"word/media/image24.png","imgOriW":175,"imgOriH":51})
![](https://wkrtcs.bdimg.com/rtcs/image?w=17.47&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"17.47","h":"18.73","dataType":"wmf","c":"word/media/image25.png","imgOriW":34,"imgOriH":37})
![](https://wkrtcs.bdimg.com/rtcs/image?w=17.47&md5sum=629036e248e52bee6d1b33e2bd060b80&sign=d8619f5ddc&rtcs_flag=2&rtcs_ver=3.2&l=webapp&bucketNum=89&ipr={"t":"img","r":"r_4","w":"17.47","h":"18.73","dataType":"wmf","c":"word/media/image26.png","imgOriW":34,"imgOriH":37})
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