4. Nizovi i redovi - 1. dio 1. Izracunajte limese sljedecih nizova (a) an ...
4. Nizovi i redovi - 1. dio 1. Izracunajte limese sljedecih nizova (a) an ...
4. Nizovi i redovi - 1. dio 1. Izracunajte limese sljedecih nizova (a) an ...
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<strong>4.</strong> <strong>Nizovi</strong> i <strong>redovi</strong> - <strong>1.</strong> <strong>dio</strong><br />
<strong>1.</strong> Izračunajte <strong>limese</strong> sljedećih <strong>nizova</strong><br />
(a) <strong>an</strong> = 2n3 − 1<br />
;<br />
2 − n3 (b) <strong>an</strong> =<br />
3<br />
2 arctg n ;<br />
(c) <strong>an</strong> = n2 (n 2 + 1)<br />
2 n (n 2 − 1) ;<br />
(d) <strong>an</strong> = (n + 1)(3n + 1)<br />
2 · 3n ;<br />
+ 1<br />
<br />
(e) <strong>an</strong> = 1 − 1<br />
n ;<br />
3n<br />
n n + 1<br />
(f) <strong>an</strong> = ;<br />
n − 1<br />
(g) <strong>an</strong> =<br />
(n+1)<br />
2n + 3<br />
;<br />
2n + 1<br />
(h) <strong>an</strong> = n[ln(n + 3) − ln n];<br />
(i) <strong>an</strong> =<br />
(j) <strong>an</strong> = n n<br />
2n <br />
ln 1 + 1<br />
n+1 ;<br />
2n<br />
<br />
sin 2<br />
n ;<br />
(k) <strong>an</strong> = 2n+1 + 3 n+1<br />
2 n + 3 n ;<br />
(l) <strong>an</strong> = (−3)n + 4 n<br />
(−3) n+1 + 4 n+<strong>1.</strong><br />
1
2. Izračunajte <strong>limese</strong> sljedećih <strong>nizova</strong><br />
(a) <strong>an</strong> = 1<br />
n 3<br />
(b) <strong>an</strong> = 1<br />
n 2<br />
(c) <strong>an</strong> = 1<br />
n 3<br />
n<br />
k(k + 1);<br />
k=1<br />
n<br />
k;<br />
k=1<br />
n<br />
k 2 ;<br />
k=1<br />
(d) <strong>an</strong> = 1<br />
n + 1<br />
(e) <strong>an</strong> = 1<br />
n 3<br />
k=2<br />
n<br />
k=1<br />
n<br />
(2k − 1) −<br />
k=1<br />
k<br />
i.<br />
i=1<br />
2n + 1<br />
;<br />
2<br />
3. Izračunajte <strong>limese</strong> sljedećih <strong>nizova</strong><br />
n<br />
<br />
(a) <strong>an</strong> = 1 − 1<br />
k2 <br />
;<br />
(b) <strong>an</strong> =<br />
(c) <strong>an</strong> =<br />
(d) <strong>an</strong> =<br />
n<br />
k=2<br />
n<br />
k=2<br />
n<br />
k=1<br />
n+1<br />
<br />
(e) <strong>an</strong> = ln<br />
k=2<br />
<br />
(f) <strong>an</strong> = n<br />
k 3 − 1<br />
k 3 + 1 ;<br />
k 2 + k − 2<br />
k(k + 1) ;<br />
1<br />
k · (k + 1) ;<br />
<br />
1 − 1<br />
k2 <br />
;<br />
ln 1<br />
2 +<br />
n<br />
<br />
(k + 1)2<br />
ln .<br />
k(k + 2)<br />
k=1<br />
<strong>4.</strong> Odredite sva gomiliˇsta niza<br />
(a) <strong>an</strong> = 3n2 + 2n<br />
n 2 − 1<br />
· 1 + (−1)n<br />
2<br />
2<br />
+ 1 − (−1)n<br />
;<br />
n
(b) <strong>an</strong> = 1 + 1<br />
<br />
cos nπ.<br />
n<br />
5. Zad<strong>an</strong> je niz<br />
<strong>an</strong> = (1 − a)n2 + 2n + b<br />
<strong>an</strong>2 .<br />
+ n + 1<br />
Odredite a i b takve da je lim <strong>an</strong> = 2 i a1 = 0.<br />
n→∞<br />
6. Zad<strong>an</strong>i su nizovi<br />
bn =<br />
1<br />
c(c + 1) +<br />
<strong>an</strong> =<br />
cn 2 + 1<br />
(c + 3)n 2 + cn + 4<br />
1<br />
+ · · · +<br />
(c + 1)(c + 2)<br />
<strong>an</strong><br />
Odredite c > 0 takvo da je lim<br />
n→∞ bn<br />
7. Odredite <strong>limese</strong> sljedećih <strong>nizova</strong><br />
(a) <strong>an</strong> =<br />
(b) <strong>an</strong> =<br />
3√ n 2 sin n<br />
n + 1 ;<br />
n sin(n!)<br />
n 2 + 1 .<br />
8. Odredite <strong>limese</strong> sljedećih <strong>nizova</strong><br />
(a) <strong>an</strong> =<br />
(b) <strong>an</strong> =<br />
1<br />
3√ n 3 + 1 +<br />
2<br />
√ n 2 + 1 +<br />
1<br />
3√ n 3 + 2 + · · · +<br />
2<br />
<br />
n 2 + 1<br />
2<br />
= <strong>4.</strong><br />
i<br />
1<br />
(c + n − 1)(c + n) .<br />
1<br />
3√ n 3 + n ;<br />
+ · · · + <br />
2<br />
n2 + 1<br />
n<br />
.<br />
3