题目
题型：不详难度：来源：
A．
| B．
| C．
| D．
|
答案
由点到直线的距离公式可得d=
| |2x-y-4| | ||
|
| |2x-x2-4| | ||
|
| |-(x-1)2-3| | ||
|
3
| ||
| 5 |
∴抛物线y=x2上的点到直线2x-y=4的最短距离是
3
| ||
| 5 |
故选B．
核心考点
举一反三
| x2 |
| 4 |
| y2 |
| a2 |
| x2 |
| a |
| y2 |
| 2 |
| A．1 | B．-1 | C．±1 | D．2 |
=0，则 A．
| B．
| C．
| D．
|
| |2x-y-4| | ||
|
| |2x-x2-4| | ||
|
| |-(x-1)2-3| | ||
|
3
| ||
| 5 |
3
| ||
| 5 |
| x2 |
| 4 |
| y2 |
| a2 |
| x2 |
| a |
| y2 |
| 2 |
| A．1 | B．-1 | C．±1 | D．2 |
=0，则