| 1 | 1 | |||
f(x) = | , f(x + h) = | |||
| x2 | (x + h)2 |
| f(x + h) − f(x) | |
= | |
| h |
| x2 (x + h)2 | ||||||||||||||||||
= | * | = | |||||||||||||||||
| h | x2 (x + h)2 |
| x2 − (x + h)2 | x2 − x2 − 2hx − h2 | |||
= | = | = | ||
| h x2 (x + h)2 | h x2 (x + h)2 |
| h (−2x − h) | −2x − h | |||
= | = | |||
| h x2 (x + h)2 | x2 (x + h)2 |
| −2x − h | −2x | −2 | ||||
limh→0 | = | = | ||||
| x2 (x + h)2 | x4 | x3 |