名校
1 . 在用二分法求方程
在区间
内的近似解时,先将方程变形为
,构建![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd3c988d875438535244ee2b092a779b.png)
,然后通过计算以判断
及
的正负号,再按步骤取区间中点值,计算中点的函数近似值,如此往复缩小零点所在区间,计算得部分数据列表如下:
(1)判断
及
的正负号;
(2)请完成上述表格,在空白处填上正确的数字;
(3)若给定的精确度为0.1,则到第几步骤即可求出近似值?此时近似值为多少?
(4)若给定的精确度为0.01,则需要到第几步骤才可求出近似值?近似值为多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ede903dc248c3730c50ed3f2ebacd4c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2be3ad3dd6803d92df6ff8a80cd35095.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/700c770c6ffdf0e7b9ee192dd82dc422.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd3c988d875438535244ee2b092a779b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/507a6315e40abb76025ce73e86e34067.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6e1a1611f320c0f358df77aaae3f942.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9cf59c5075f9e6fdf3782b6c0e528237.png)
步骤 | 区间左端点 | 区间右端点 |
| 中点 |
1 | 2 | 3 | 2.5 | -0.102 |
2 | 0.189 | |||
3 | 2.625 | 0.044 | ||
4 | 2.5 | 2.625 | 2.5625 | -0.029 |
5 | 2.5625 | 2.625 | 2.59375 | 0.008 |
6 | 2.5625 | 2.59375 | 2.578125 | -0.011 |
7 | 2.578125 | 2.59375 | 2.5859375 | -0.001 |
8 | 2.5859375 | 2.59375 | 2.58984375 | 0.003 |
9 | 2.5859375 | 2.58984375 | 2.587890625 | 0.001 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6e1a1611f320c0f358df77aaae3f942.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9cf59c5075f9e6fdf3782b6c0e528237.png)
(2)请完成上述表格,在空白处填上正确的数字;
(3)若给定的精确度为0.1,则到第几步骤即可求出近似值?此时近似值为多少?
(4)若给定的精确度为0.01,则需要到第几步骤才可求出近似值?近似值为多少?
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