NCERT Solutions
Board Paper Solutions
Ask & Answer
School Talk
Login
GET APP
Login
Create Account
Popular
Latest
Expert Answers
ALL
Divya Mahesh
Subject: Maths
, asked on 23/10/17
If the ratio of the sum of the first 12 terms to the sum of the first 18 terms of an AP is 4:9, then find the ratio of the 11th term to 32nd term.
Answer
1
Isha Kulkarni
Subject: Maths
, asked on 22/10/17
If a, b, c, d, are in g.p then prove that a2-b2, c2-b2, c2 -d2 are in g.p
Answer
1
Erw Trjerth
Subject: Maths
, asked on 22/10/17
Experts please give me some questions involving sequence and series of complex numbers along with the answer
Answer
1
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Question No. 2
2. The least value of
2
log
100
a
-
log
a
0
.
0001
,
a
>
1
i
s
Answer
1
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q. If a, b, c are distinct positive real numbers in G.P. and log
c
a, log
b
c, log
a
b are in A.P. then find the common difference of this A.P.
Answer
1
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q. If
∑
r
=
1
n
T
r
=
n
8
( n + 1) (n + 2) (n + 3), then find
∑
r
=
1
n
1
T
r
.
Answer
1
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q. If X
1
,X
2
, X
3
, ...X
n
are in H.P, then prove that X
1
X
2
+
X
2
X
3
+ X
3
X
4
+ ... + X
n
- 1X
n
= (n-1)X
1
X
n
.
Answer
1
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q no 15
Q15. The value of
∑
r
=
2
100
3
r
2
-
2
r
r
r
+
1
r
+
2
is equal to
(A)
1
2
-
3
100
100
101
(B)
3
2
-
3
101
101
102
(C)
3
2
-
3
100
100
101
(D) none of these
Answer
2
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q. If 1.(0!) + 3. (1!) + 7. (2!) + 13.(3!) + 21.(4!) + .....upto terms = (4000)4000! , then the value of n is
(A) 4000 (B) 4001 (C) 3999 (D) none of these
Answer
2
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q no 7
Q7. If S
n
=
=
∑
r
=
1
n
1
+
2
+
2
2
.
.
.
r
terms
2
r
, then Sn is equal to
(A) 2
n
– (n +1) (B) n × (n +1) /2
(C) (n
2
+ 3n +2 )/6 (D) n – 1 + (1/2
n
)
Answer
3
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q. If a, b, c are three positve real numbers, then the minimum value of the expression
b
+
c
a
+
c
+
a
b
+
a
+
b
c
is
(A) 1 (B) 2 (C) 3 (D) 6
Answer
2
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q.(i) If a
1
, a
2
, ...., a
n
are n positive real numbers such that a
1
,a
2
, .....a
n
= 1, show that ( 1 + a
1
) (1 + a
2
) ....
( 1+a
n
)
≥
2
n
.
(ii) If n is a positive integer , prove that 2
n
>
1+ n
2
n
-
1
; n
>
1.
Answer
1
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q no 2
Q2. Show that
a
1
a
2
+
a
2
a
3
+
a
3
a
4
... +
a
n
-
1
a
n
+
a
n
a
1
>
n
,
where
a
1
,
a
2
.
.
.
an
are different positive integers.
Answer
1
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Q. The sum of the series 1 + 2 (1 + 1/n) + 3( 1+1/n)
2
+ ....
∞
is given by
(A) n
2
+ 1 (B) n (n+1) (C) n ( 1+1/n)
2
(D) n
2
Answer
2
Kshitiz Anand
Subject: Maths
, asked on 16/10/17
Qno 6
Q6. Show that (1 + 3
–1
) (1 + 3
–2
) (1 + 3
–4
) (1 + 3
–8
) ...
(
1
+
3
-
2
n
)
=
3
2
1
-
3
-
2
n
+
1
.
Answer
1
Prev
5
6
7
8
9
Next
What are you looking for?
2. The least value of
Q15. The value of is equal to
(A) (B)
(C) (D) none of these
(A) 4000 (B) 4001 (C) 3999 (D) none of these
Q7. If Sn = , then Sn is equal to
(A) 2n – (n +1) (B) n × (n +1) /2
(C) (n2 + 3n +2 )/6 (D) n – 1 + (1/2n)
(A) 1 (B) 2 (C) 3 (D) 6
( 1+an) 2n .
(ii) If n is a positive integer , prove that 2n 1+ n ; n 1.
Q2. Show that ... + are different positive integers.
(A) n2 + 1 (B) n (n+1) (C) n ( 1+1/n)2 (D) n2
Q6. Show that (1 + 3–1) (1 + 3–2) (1 + 3–4) (1 + 3–8) ... .