近视眼镜的度数y(度) | 200 | 250 | 400 | 500 | 1000 |
镜片焦距x(米) | 0.50 | 0.40 | 0.25 | 0.20 | 0.10 |
x | -4 | -2 | -1 | 1 | 2 | 4 |
y=ax+b | -6 | -4 | -3 | -1 | 0 | 2 |
y= | -2 | -4 | -8 | 8 | 4 | 2 |
|
| 2.5 | 3 | 3.5 | 4 | 4.5 | 5 |
|
|
| 6 |
| 2 |
| 1.2 | 1 |
|