MCS 351 ENGINEERING MATHEMATICS SOLUTION OF ...
MCS 351 ENGINEERING MATHEMATICS SOLUTION OF ...
MCS 351 ENGINEERING MATHEMATICS SOLUTION OF ...
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∞∑<br />
4. Let<br />
n=0<br />
n n<br />
n! (z + 2i)n . First of all, center is −2i since<br />
Let z n = nn<br />
n! (z + 2i)n .As<br />
lim<br />
n→∞<br />
∣<br />
n n<br />
n!<br />
(n+1) ( n+1)<br />
(n+1)!<br />
radius of convergence is 1 e .<br />
| = lim<br />
n→∞<br />
z + 2i = 0 ⇒ z = −2i.<br />
n n (n + 1)<br />
= lim<br />
(n + 1) n+1 n→∞<br />
n n<br />
(n + 1) n = lim<br />
( n ) n 1 =<br />
n→∞ n + 1 e ,<br />
5. Let<br />
∞∑<br />
n=0<br />
n!<br />
n n (z + 1)n . The center point is −1 since<br />
Let z n = n!<br />
n n (z + 1) n . Then<br />
lim<br />
n→∞<br />
we say that radius of convergence is e.<br />
∣<br />
z + 1 = 0 ⇒ z = −1.<br />
n!<br />
n n<br />
(n+1)!<br />
(n+1) ( n+1)<br />
| = lim<br />
n→∞<br />
(n + 1) n = e,<br />
n<br />
15.3<br />
1-3 Radius of convergence by differentiation or integration :<br />
1. Let<br />
∞∑<br />
n=2<br />
n(n − 1)<br />
3 n (z − 2i) n . Since<br />
lim<br />
n→∞<br />
we say that radius of convergence is 1 4 .<br />
∣<br />
4 n<br />
n(n+1)<br />
4 n+1<br />
(n+1)(n+2)<br />
n + 2<br />
| = lim<br />
n→∞ 4n = 1 4 ,<br />
2. Let<br />
∞∑<br />
n=1<br />
4 n<br />
n(n + 1) zn . Because<br />
radius of convergence is found that 3.<br />
3. Let<br />
∞∑<br />
n=1<br />
lim ∣ n(n−1)<br />
3 n<br />
n→∞<br />
| = lim<br />
n(n+1) n→∞<br />
3 n+1<br />
3n − 3<br />
n + 1 = 3,<br />
n<br />
2 n (z + i)2n . Radius of convergence for this serie is 2 in that<br />
lim<br />
n→∞<br />
∣<br />
n<br />
2 n<br />
n+1<br />
n→∞<br />
2 n+1 | = lim<br />
47<br />
2n<br />
n + 1 = 2.