P 0.1 Stabilişti natura şsi suma seriilor: a) Σ 1 n\ ; b) Σ arctan 1 n# + n ...
P 0.1 Stabilişti natura şsi suma seriilor: a) Σ 1 n\ ; b) Σ arctan 1 n# + n ...
P 0.1 Stabilişti natura şsi suma seriilor: a) Σ 1 n\ ; b) Σ arctan 1 n# + n ...
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P <strong>0.1</strong> Stabili¸ti <strong>natura</strong> ¸si <strong>suma</strong> <strong>seriilor</strong>:<br />
a)<br />
1X<br />
ln 1 + 1<br />
n<br />
; b)<br />
1X<br />
1<br />
<strong>arctan</strong><br />
n2 ;<br />
+ n + 1<br />
c)<br />
g)<br />
i)<br />
n=1<br />
d)<br />
1X<br />
n=1<br />
1X<br />
n=1<br />
1X<br />
n=1<br />
( 1) n<br />
; e)<br />
2n 1<br />
n=1<br />
1X<br />
n=1<br />
2n 1<br />
2 n ; f)<br />
p n + 2 2 p n + 1 + p n ; h)<br />
2n + 1<br />
; j)<br />
n (n + 1) (n + 2)<br />
P 0.2 Stabili¸ti <strong>natura</strong> <strong>seriilor</strong><br />
a)<br />
1X 9 + n<br />
;<br />
2n + 1<br />
b)<br />
1X<br />
n=1<br />
d)<br />
1X<br />
n=1<br />
n=1<br />
n<br />
; e)<br />
n + 1<br />
1X<br />
n=2<br />
1X<br />
n=1<br />
1X<br />
n=1<br />
1<br />
; k)<br />
n ln n<br />
2n + 3n 2n+1 ; c)<br />
+ 3n+1 1X<br />
n=2<br />
1X<br />
n=1<br />
1<br />
np ln n ; f)<br />
P 0.3 Stabili¸ti <strong>natura</strong> <strong>seriilor</strong>:<br />
1X 1<br />
a)<br />
2n<br />
;<br />
1<br />
1X 1<br />
b)<br />
2 ;<br />
(2n 1)<br />
c)<br />
j)<br />
d)<br />
g)<br />
1X<br />
n=1<br />
1X<br />
n=2<br />
m)<br />
1X<br />
n=1<br />
n=1<br />
1<br />
p n + 1 + p n ; e)<br />
1<br />
2n ; h)<br />
n + 1<br />
1<br />
p 3<br />
n p ; k)<br />
n 1<br />
1X<br />
n=1<br />
o)<br />
1X<br />
n=1<br />
n=1<br />
1X<br />
n=1<br />
1X<br />
n=1<br />
1X<br />
n=2<br />
ln 1<br />
1<br />
(3n 2) (3n + 1) ;<br />
1<br />
n 2<br />
1<br />
n + p 2 n + p 2 + 1 ;<br />
1X<br />
n=3<br />
1<br />
n (ln n) ln ln n :<br />
1<br />
p 2n + 1 p 2n 1 ;<br />
1X<br />
n=1<br />
1X<br />
n=2<br />
n cos2 (n =3)<br />
2n ; f)<br />
1<br />
3n + n2 ; i)<br />
+ n<br />
(ln n) 10<br />
n 1:1 ; l)<br />
1X<br />
n=1<br />
2 p e 2 3 p e ::: 2 n p e ; n)<br />
1X<br />
n=1<br />
sin 1<br />
; p)<br />
n<br />
1X<br />
n=1<br />
4p<br />
n2 1<br />
p ; q)<br />
n4 1<br />
1<br />
1<br />
np n :<br />
1<br />
p 4n 2 1 ;<br />
1X<br />
n=1<br />
1X<br />
n=2<br />
p n 2 + n<br />
3p n 5 n ;<br />
p 7n<br />
n 2 + 3n + 5 ;<br />
1<br />
1 + p 2 + 3p 3 + ::: + np n ;<br />
1X<br />
n=1<br />
1X<br />
n=1<br />
e n<br />
n (1 + 2 n )<br />
3p n 2 1<br />
p n 3 1 :<br />
;
2<br />
P 0.4 Stabili¸ti <strong>natura</strong> <strong>seriilor</strong>:<br />
1X 100<br />
a)<br />
n<br />
;<br />
n!<br />
1X (n!)<br />
b)<br />
2<br />
;<br />
(2n)!<br />
1X<br />
c)<br />
f)<br />
o)<br />
n=1<br />
1X<br />
n=1<br />
k)<br />
m)<br />
1X<br />
n=1<br />
(n!) 2<br />
2 n2 ; g)<br />
1X<br />
n=1<br />
1X<br />
n=1<br />
2<br />
n=1<br />
1X<br />
n=1<br />
3p 2 2<br />
1<br />
(2n2 + n + 1) n+1<br />
2<br />
3p n 3 + n 2 + 1<br />
n=1<br />
n!<br />
; d)<br />
nn 1X<br />
n=1<br />
100 101 ::: (100 + n)<br />
; h)<br />
1 3 ::: (2n 1)<br />
5p 2 ::: 2<br />
; n)<br />
1X<br />
n=1<br />
2n+1 p 2 ; l)<br />
3p n 3 n 2 + 1 n<br />
; p)<br />
2 n n!<br />
n n ; e)<br />
1X<br />
n=1<br />
1X<br />
n=1<br />
1 3 + 2 3 + ::: + n 3<br />
n 3<br />
1X<br />
n=1<br />
P 0.5 Stabili¸ti <strong>natura</strong> seriei cu termenul general<br />
un =<br />
n n+1<br />
e n (n + 1)! :<br />
P 0.6 Pentru …ecare a > 0; studia¸ti <strong>natura</strong> seriei:<br />
1X 1<br />
a)<br />
an ;<br />
+ n<br />
1X a<br />
b)<br />
n<br />
p ;<br />
n!<br />
1X<br />
c)<br />
e)<br />
1X<br />
n=1<br />
n=1<br />
n2 + n + 1<br />
n2 a<br />
n=1<br />
n<br />
; f)<br />
1X<br />
n=1<br />
n=1<br />
3n 2n ; g)<br />
+ an a ln n ; d)<br />
1X<br />
n=1<br />
3 n n!<br />
n n ;<br />
4 7 ::: (4 + 3n)<br />
2 6 ::: (2 + 4n) ;<br />
n 2<br />
2 + 1<br />
n<br />
n<br />
4<br />
(3n) 2<br />
n ;<br />
n<br />
;<br />
q<br />
(16n 2 + 5n + 1) n+1<br />
1X<br />
n=1<br />
P 0.7 Pentru …ecare a; b > 0; studia¸ti <strong>natura</strong> seriei:<br />
1X<br />
a)<br />
1X<br />
1X<br />
n=1<br />
an an ; b)<br />
+ bn d)<br />
n=1<br />
1X<br />
n=1<br />
n=1<br />
2n an ; c)<br />
+ bn n=1<br />
(2a + 1) (3a + 1) (na + 1)<br />
(2b + 1) (3b + 1) (nb + 1) :<br />
1X<br />
n=1<br />
an ;<br />
nn p p<br />
n + 1 n<br />
na :<br />
anbn an ;<br />
+ bn P 0.8 Pentru …ecare a; b 2 R, a > 0; stabili¸ti <strong>natura</strong> seriei:<br />
1X (a + 1) (a + 2)<br />
n!<br />
(a + n) 1<br />
:<br />
nb :
P 0.9 Fie (un) n 1 un ¸sir de numere reale strict pozitive ¸si un num¼ar<br />
real. Pentru …ecare num¼ar <strong>natura</strong>l n 1 punem<br />
n = un+1<br />
un<br />
n<br />
n + 1<br />
Ar¼ata¸ti c¼a:<br />
(i) Dac¼a > 1 ¸si exist¼a un num¼ar <strong>natura</strong>l n0 cu proprietatea c¼a<br />
atunci seria 1P<br />
n=1<br />
n 0; oricare ar … n n0;<br />
un este convergent¼a.<br />
(ii) Dac¼a 1 ¸si exist¼a un num¼ar <strong>natura</strong>l n0 cu proprietatea c¼a<br />
atunci seria 1P<br />
n=1<br />
n > 0; oricare ar … n n0;<br />
un este divergent¼a.<br />
P <strong>0.1</strong>0 Stabili¸ti <strong>natura</strong> <strong>seriilor</strong>:<br />
1X (2n 1)!! 1<br />
a)<br />
; b)<br />
(2n)!! 2n + 1<br />
n=1<br />
n=1<br />
1X<br />
n=1<br />
(2n 1)!!<br />
; c)<br />
(2n)!!<br />
P <strong>0.1</strong>1 Pentru …ecare a > 0; studia¸ti <strong>natura</strong> <strong>seriilor</strong>:<br />
1X<br />
1X<br />
n!<br />
a)<br />
; b) a<br />
a(a + 1)::: (a + n)<br />
n=1<br />
:<br />
1X<br />
n=1<br />
1 1<br />
(1+ +:::+ 2 n) ; c)<br />
P <strong>0.1</strong>2 Dac¼a ; ; ; x 2]0; +1[; stabili¸ti <strong>natura</strong> seriei<br />
1X ( + 1) ::: ( + n 1) ( + 1) ::: (<br />
( + 1) ::: ( + n 1)<br />
+ n 1)<br />
x n<br />
n=1<br />
(numit¼a seria hipergeometric¼a a lui Gauss) :<br />
P <strong>0.1</strong>3 S¼a se stabileasc¼a <strong>natura</strong> <strong>seriilor</strong>:<br />
1X<br />
1X<br />
a)<br />
c)<br />
1X<br />
n=1<br />
n=1<br />
( 1) n+1 (n + 1) n+1<br />
n n+2 ; b)<br />
( 1) n+1 2n + 1<br />
3 n ; d)<br />
f)<br />
1X<br />
n=1<br />
1X<br />
n=2<br />
n=1<br />
( 1) n+1 1<br />
p n (n + 1) ; g)<br />
( 1) n+1 1<br />
; e)<br />
ln n<br />
1<br />
n!<br />
1X<br />
n=1<br />
n<br />
e<br />
n<br />
:<br />
a n n!<br />
n n :<br />
( 1) n+1 n 1<br />
(n + 1)<br />
nn+1 ;<br />
3<br />
1X<br />
( 1)<br />
n=1<br />
n+1 1<br />
n(n + 1) ;<br />
1X<br />
( 1) n+1<br />
p<br />
n<br />
n + p 5 ;<br />
n=1
4<br />
h)<br />
1X<br />
n=1<br />
( 1) n+1 (2n 1)!!<br />
:<br />
(2n)!!<br />
P <strong>0.1</strong>4 S¼a se stabileasc¼a <strong>natura</strong> <strong>seriilor</strong>:<br />
1X<br />
a) ( 1) n(n+1)<br />
2<br />
1X<br />
n=1<br />
n=1<br />
n100 ; b)<br />
2n n=1<br />
( 1) n(n+1)<br />
2 sin n p n + 1 :<br />
P <strong>0.1</strong>5 Determina¸ti valorile lui x 2 R pentru care seriile urm¼atoare<br />
sunt convergente:<br />
1X 1<br />
a)<br />
2 ;<br />
(n + jxj) n=1<br />
1X ( 1)<br />
b)<br />
n=1<br />
n x2n 2n (2n 1) ;<br />
1X x<br />
c)<br />
(1 + nx2 ) p ;<br />
n<br />
1X x<br />
d)<br />
1 + jxj p n :<br />
n=1<br />
n=1<br />
P <strong>0.1</strong>6 Pentru …ecare a 2 R, stabili¸ti <strong>natura</strong> <strong>seriilor</strong>;<br />
1X<br />
a) cos (na) sin a<br />
1X<br />
; b) sin (na) sin<br />
n a<br />
n ;<br />
c)<br />
1X<br />
n=1<br />
cos (na) tan a2<br />
; d)<br />
n<br />
1X<br />
e)<br />
n=1<br />
n=1<br />
1X<br />
n=1<br />
n<br />
( 1)<br />
[ 4 ] n + a<br />
ln 2<br />
n :<br />
sin (na) tan a<br />
n ;<br />
P <strong>0.1</strong>7 S¼a se arate c¼a pentru orice num¼ar <strong>natura</strong>l p are loc inegalitatea<br />
1X 1<br />
(n + 1) pp < p:<br />
n<br />
n=1