| 4 n2 + 4 n + 4 − ( 4 n2 + 2n − 1) | ||
an = | = | |
| √4 n2 + 4 n + 4 + √4 n2 + 2n − 1 |
| 2 n + 5 | ||
= | = | |
| √ 4n2 + 4 n + 4 + √4 n2 + 2n − 1 |
| 2 + 5n | ||
= | ||
| √ 4 + 4n + 4n2 + √ 4 + 2n − 1n2 |
| 2 | ||
lim an = | = 0,5 | |
| 2 + 2 |
| a2 − b2 | ||
W takich przykładach stosujemy wzór a − b = | ||
| a + b |