Oblicz granice
Xxx: Oblicz granice
Lim n! − (n−1) ! + (n−2) ! / −2n! + 2(n−2)!
Hmm... nie wiem czy da się jakoś inaczej zapisać n! ? (n−2)(n−1)n ?
1 sty 22:08
Student:
n! = (n−2)! * (n−1) * n
1 sty 22:17
Student:
licznik:
n! − (n−1)! + (n−2)! = (n−2)!*(n−1)*n − (n−2)!*(n−1) + (n−2)! =
= (n−2)![(n−1)*n − (n−1) + 1] = (n−2)![n
2−n−n+1+1] = (n−2)![n
2−2n+2]
mianownik:
−2n! + 2(n−2)! = −2(n−2)!*(n−1)*n + 2(n−2)! = (n−2)![−2(n−1)*n+2] =
= (n−2)![−2(n
2−n) + 2] = (n−2)![−2n
2+2n+2]
zatem
licznik | | (n−2)![n2−2n+2] | | n2−2n+2 | |
| = |
| = |
| |
mianownik | | (n−2)![−2n2+2n+2] | | −2n2+2n+2 | |
z tego juz policzysz granice.
1 sty 22:19
Basia:
n!−(n−1)!+(n−2)! | |
| = |
−2n! + 2(n−2)! | |
(n−2)![(n−1)*n −(n−1)+1] | |
| = |
(n−2)![−2(n−1)*n+2] | |
n2−2n+2 | | 1 | | 1 | |
| → |
| = − |
| |
−2n2−2n+2 | | −2 | | 2 | |
1 sty 22:19