1 + n | ||
an= | ||
1+ n2 |
5+10+15....+5n | ||
an= | ||
n+3 |
2+n | 1+n | |||
an+1−an= | − | = | ||
2+2n+n2 | 1+n2 |
2+n+2n2+n3−(2+4n+3n2+n3) | ||
= | = | |
(2+2n+n2)(1+n2) |
−n2−3n | ||
= | <0, ciąg jest malejący | |
(2+2n+n2)(1+n2) |
| 5n2+5n | ||||||||||||
an= | = | ||||||||||||
n+3 | 2n+6 |
5n2+15n+10 | 5n2+5n | |||
an+1−an= | − | = | ||
2n+8 | 2n+6 |
5(n+1)(n+2)(2n+6)−5(n+1)n(2n+8) | 5(n+6)(n+1) | |||
= | = | >0 | ||
(2n+8)(2n+6) | 2(n+4)(n+3) |