Pour simplifier l'écriture, on pose X = eˣ, soit e²ˣ = X² et e³ˣ = X³
Quand x --> 0, X --> 1
(X² - 1)/(X³ - 1)
= (X - 1)(X + 1)/(X - 1)(X² + X + 1)
= (X + 1)/(X² + X + 1)
tend vers 2/3
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ramzi13
2x x x x e -1 ( e )² -1² (e -1)(e +1) lim ............. = lim .................. = lim ............................. 3x x→0 x x→0 x 2x x x→0 e -1 (e )³ -1³ (e -1) (e +e +1)
x e +1 1+1 2 x 2x =lim ...................... = ...........=....... ( lim e =1 , lim e = 1 x→0 2x x 1+1+1 3 x→0 x→0 e + e +1
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Bonjour,(e²ˣ - 1)/(e³ˣ - 1)
Pour simplifier l'écriture, on pose X = eˣ, soit e²ˣ = X² et e³ˣ = X³
Quand x --> 0, X --> 1
(X² - 1)/(X³ - 1)
= (X - 1)(X + 1)/(X - 1)(X² + X + 1)
= (X + 1)/(X² + X + 1)
tend vers 2/3
e -1 ( e )² -1² (e -1)(e +1)
lim ............. = lim .................. = lim .............................
3x x→0 x x→0 x 2x x
x→0 e -1 (e )³ -1³ (e -1) (e +e +1)
x
e +1 1+1 2 x 2x
=lim ...................... = ...........=....... ( lim e =1 , lim e = 1
x→0 2x x 1+1+1 3 x→0 x→0
e + e +1
donc :