Visvesvaraya National Institute of Technology, Nagpur
Department of Mathematics 1
Mathematics-I (MAL-101)
Assignment on sequence, series, improper integrals
Sequences:
1. Discuss the convergence or otherwise of the following sequences.
() ((2n)(vi)
n!n! +2
2. Show that the sequence {r"} (i) diverges to +oo if r > 1, (ii) converges to 1 if r = 1, (ii)
converges to 0 if -1 <r<1,(iv) is oscillating finitely if r = -1, (v) is oscillating infinitely
ifr<-1.
3. Prove that the sequence {an} defined by a1 = v2, dn+1 = V24n for all n 1, is convergent
and the limit of the sequence is 2.
4. Using Sandwich theorem, prove that 1
?+1 n +2 Vn2+n
5. Prove that the sequence {a,} defined by aj = V7, an+1 = V7 +an for all n, is convergent
and the limit of the sequence is the positive root of the equation z - t -7= 0.
6. Prove that the sequence {an} defined by a1 = 0, a2 = 1. and an+2 = (an+1 +an) for all
n1, is a Cauchy sequence.
Infinite Series:
7. Examine the behaviour of the following series. Also find their sum, if exists.
2-1
n=l n=l
i-1)"1
6-1
n=l| n=0
8. Examine the behaviour of the following series (converges or diverges):
2n-1 n!2"
.. (V) 2 n
nn+)(n 1)(n +2) +Vn+11 n=l
) )G)G9
12 12.22 12.32.52 2! 3!
1
(V1) 2 2 2 t 6 t (ix) 1 +5+ + (x) P> 0
2 (lnn)p
T=2
(-1)"-n (xi) 1 +2) +1+2+3)1 +2+3+4) +
-
n=
Power Series:
1
9. Find the radius and interval of the convergence of the following power series:
(n +1) 1.3 2 1.3.53 (ii) +3)"
(n +2)(n +3)"
n=l
2T 25t 25+ n=l
v) 4r-8)".
8
n=l n=l
10. Find the radius and the circle of the convergence the following power series:
n2
3n + o" Gi) (GV)
2 (2n)!
n=0 n=0
Improper Inte rals
11. Examine the convergence of the following integrals:
dz
o ) ar n hr (ii)log,(sin z) dr
da
iv) Jo cos a - cos t
(
dr(vi) dr (vi) 1+:
d
da Sin a da
(ii
+ ] ), zydr ()(1+z)2+ z)Vz(1 -
r)
(i) Inz dz.