Page 1
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Morning
Time : 3 hrs. M.M. : 300
IMPORTANT INSTRUCTIONS:
(1) The test is of 3 hours duration.
(2) The Test Booklet consists of 90 questions. The maximum marks are 300.
(3) There are three parts in the question paper consisting of Mathematics, Physics and Chemistry
having 30 questions in each part of equal weightage. Each part (subject) has two sections.
(i) Section-A: This section contains 20 multiple choice questions which have only one correct
answer. Each question carries 4 marks for correct answer and –1 mark for wrong answer.
(ii) Section-B: This section contains 10 questions. In Section-B, attempt any five questions out
of 10. The answer to each of the questions is a numerical value. Each question carries 4 marks
for correct answer and –1 mark for wrong answer. For Section-B, the answer should be
rounded off to the nearest integer.
Page 2
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Morning
Time : 3 hrs. M.M. : 300
IMPORTANT INSTRUCTIONS:
(1) The test is of 3 hours duration.
(2) The Test Booklet consists of 90 questions. The maximum marks are 300.
(3) There are three parts in the question paper consisting of Mathematics, Physics and Chemistry
having 30 questions in each part of equal weightage. Each part (subject) has two sections.
(i) Section-A: This section contains 20 multiple choice questions which have only one correct
answer. Each question carries 4 marks for correct answer and –1 mark for wrong answer.
(ii) Section-B: This section contains 10 questions. In Section-B, attempt any five questions out
of 10. The answer to each of the questions is a numerical value. Each question carries 4 marks
for correct answer and –1 mark for wrong answer. For Section-B, the answer should be
rounded off to the nearest integer.
MATHEMATICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer:
1. The number of elements in the set
? ?
? ?
4 2 6
0,2 : 3cos 5cos 2sin 2 0 = ? ? ? ? - ? - ? + = S
is
(1) 10 (2) 8
(3) 12 (4) 9
Answer (4)
Sol. 3cos
4
? – 5cos
2
? – 2sin
6
? + 2 = 0
? cos
2
?[3cos
2
? – 5] – 2sin
6
?
+ 2 = 0
? (1 – sin
2
?) (3 – 3sin
2
? – 5) – 2sin
6
?
+ 2 = 0
? (sin
2
? – 1) (3sin
2
? + 2) – 2sin
6
?
+ 2 = 0
Let sin
2
? = t
(t – 1) (3t + 2) – 2t
3
+ 2 = 0
(t – 1) [3t + 2 – 2 (t
2
+ t + 1)] = 0
(t – 1) [2t
2
– t] = 0
1
0, 1 ,
2
t =
? sin
2
? = 0 ? 3 solution
sin
2
? = 1 ? 2 solution
sin
2
? =
1
2
? 4 solution
? Total solution = 9
2. Let ? ? : 2, 4 ? f be a differentiable function such
that
( ) ( ) ( ) ( ) ( ) log log 1 , [2, 4] ? + + ? ?
ee
x x f x x f x f x x
with ( )
1
2
2
= f and ( )
1
4
2
= f .
Consider the following two statements :
(A) ( ) 1 , for all [2, 4] ?? f x x
(B) ( )
1
, for all [2, 4]
8
?? f x x
Then,
(1) Neither statement (A) nor statement (B) is true
(2) Only statement (B) is true
(3) Both the statements (A) and (B) are true
(4) Only statement (A) is true
Answer (3*)
Sol. f : [2, 4] ? ?
(x log e x) f?(x) + (log e x) f(x) + f(x) ? 1, x ? [2, 4]
? d [x lnx f(x) – x] ? 0 OR d (x lnx ? f(x)) ? 1
? h(x) = x lnx f(x) – x ?
? h(x) ? h(2) , x ? [2, 4]
x lnx f(x) – x ? 2 ln2f(2) – 2
? x lnx f(x) – x ? ln2 – 2, x lnx f(x) – x ? ln4 – 4
So,
ln2 2 1 ln4 4 1
()
ln ln ln ln
fx
x x x x x x
--
+ ? ? +
f(x) ? 1
&
1
()
8
fx ?
Hence both A & B are correct.
But LMVT on f(x) ? x lnx can’t be satisfied. Hence no
such f(x) exist.
3. Let R be a rectangle given by the lines x = 0, x = 2,
y = 0 and y = 5. Let A(?, 0) and B(0, ?), ? ? [0, 2]
and ? ? [0, 5], be such that the line segment AB
divides the area of the rectangle R in the ratio 4 : 1.
Then, the mid-point of AB lies on a
(1) straight line (2) parabola
(3) hyperbola (4) circle
Answer (3)
Sol.
Page 3
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Morning
Time : 3 hrs. M.M. : 300
IMPORTANT INSTRUCTIONS:
(1) The test is of 3 hours duration.
(2) The Test Booklet consists of 90 questions. The maximum marks are 300.
(3) There are three parts in the question paper consisting of Mathematics, Physics and Chemistry
having 30 questions in each part of equal weightage. Each part (subject) has two sections.
(i) Section-A: This section contains 20 multiple choice questions which have only one correct
answer. Each question carries 4 marks for correct answer and –1 mark for wrong answer.
(ii) Section-B: This section contains 10 questions. In Section-B, attempt any five questions out
of 10. The answer to each of the questions is a numerical value. Each question carries 4 marks
for correct answer and –1 mark for wrong answer. For Section-B, the answer should be
rounded off to the nearest integer.
MATHEMATICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer:
1. The number of elements in the set
? ?
? ?
4 2 6
0,2 : 3cos 5cos 2sin 2 0 = ? ? ? ? - ? - ? + = S
is
(1) 10 (2) 8
(3) 12 (4) 9
Answer (4)
Sol. 3cos
4
? – 5cos
2
? – 2sin
6
? + 2 = 0
? cos
2
?[3cos
2
? – 5] – 2sin
6
?
+ 2 = 0
? (1 – sin
2
?) (3 – 3sin
2
? – 5) – 2sin
6
?
+ 2 = 0
? (sin
2
? – 1) (3sin
2
? + 2) – 2sin
6
?
+ 2 = 0
Let sin
2
? = t
(t – 1) (3t + 2) – 2t
3
+ 2 = 0
(t – 1) [3t + 2 – 2 (t
2
+ t + 1)] = 0
(t – 1) [2t
2
– t] = 0
1
0, 1 ,
2
t =
? sin
2
? = 0 ? 3 solution
sin
2
? = 1 ? 2 solution
sin
2
? =
1
2
? 4 solution
? Total solution = 9
2. Let ? ? : 2, 4 ? f be a differentiable function such
that
( ) ( ) ( ) ( ) ( ) log log 1 , [2, 4] ? + + ? ?
ee
x x f x x f x f x x
with ( )
1
2
2
= f and ( )
1
4
2
= f .
Consider the following two statements :
(A) ( ) 1 , for all [2, 4] ?? f x x
(B) ( )
1
, for all [2, 4]
8
?? f x x
Then,
(1) Neither statement (A) nor statement (B) is true
(2) Only statement (B) is true
(3) Both the statements (A) and (B) are true
(4) Only statement (A) is true
Answer (3*)
Sol. f : [2, 4] ? ?
(x log e x) f?(x) + (log e x) f(x) + f(x) ? 1, x ? [2, 4]
? d [x lnx f(x) – x] ? 0 OR d (x lnx ? f(x)) ? 1
? h(x) = x lnx f(x) – x ?
? h(x) ? h(2) , x ? [2, 4]
x lnx f(x) – x ? 2 ln2f(2) – 2
? x lnx f(x) – x ? ln2 – 2, x lnx f(x) – x ? ln4 – 4
So,
ln2 2 1 ln4 4 1
()
ln ln ln ln
fx
x x x x x x
--
+ ? ? +
f(x) ? 1
&
1
()
8
fx ?
Hence both A & B are correct.
But LMVT on f(x) ? x lnx can’t be satisfied. Hence no
such f(x) exist.
3. Let R be a rectangle given by the lines x = 0, x = 2,
y = 0 and y = 5. Let A(?, 0) and B(0, ?), ? ? [0, 2]
and ? ? [0, 5], be such that the line segment AB
divides the area of the rectangle R in the ratio 4 : 1.
Then, the mid-point of AB lies on a
(1) straight line (2) parabola
(3) hyperbola (4) circle
Answer (3)
Sol.
1
10
4
2
20 4
1
1
2
- ??
= ? - ?? = ??
??
4 ? ?? =
Let ,
22
k
h
?
= ? =
? 4hk = 4
? 1 xy =
4. Let
? ?
? ? ? ? , 0, 1, 2 , 1 , 2 ?? = = ? ? ?
??
ij ij
S M a a i j
be a sample space and ? ? : is invertible ? A M S M
be an even. Then P(A) is equal to
(1)
16
27
(2)
47
81
(3)
49
81
(4)
50
81
Answer (4)
Sol. If M is invertible, then |M| ? 0
For |M| = 0
1.
1 1 0 0 2 2
or or
1 1 0 0 2 2
? ? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ? ?
? Total matrix = 3
2. Two 1’s and Two 0’s ? Total matrix = 4
3. Two 2’s and Two 0’s ? Total matrix = 4
4. Two 1’s and Two 2’s ? Total matrix = 4
5. One 1 and three 0’s ? Total matrix = 4
6. One 2 and Three 0’s ? Total matrix = 4
7. One 1 and one 2 and two 0’s ? Total matrix = 8
( )
31 50
1
81 81
PA = - =
5. The number of integral solution x of
2
7
2
7
log 0
23
??
+
??
??
- ??
?
??
-
?? x
x
x
is
(1) 7
(2) 8
(3) 6
(4) 5
Answer (3)
Sol.
2
7
2
7
log 0
23 x
x
x
??
+
??
??
- ??
?
??
-
??
Domain
7
0
2
x+?
–7
2
x ?
7
1
2
x+?
5
2
x
-
?
7
0
23
x
x
-
?
-
x ? 7
3
2
x ?
Domain :
7 5 3
, , 0,
2 2 2
- ? ? ? ?
- ? -
??
??
? ? ? ?
Case I :
7
01
2
x ? + ?
75
22
x - ? ? -
2
7
1
23
x
x
- ??
?
??
-
??
7
11
23
x
x
-
- ? ?
-
7 2 3
0
23
xx
x
- + -
?
-
3 10
0
23
x
x
-
?
-
7 2 3
0
23
xx
x
- - +
?
-
4
0
23
x
x
--
?
-
4
0
23
x
x
+
?
-
Page 4
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Morning
Time : 3 hrs. M.M. : 300
IMPORTANT INSTRUCTIONS:
(1) The test is of 3 hours duration.
(2) The Test Booklet consists of 90 questions. The maximum marks are 300.
(3) There are three parts in the question paper consisting of Mathematics, Physics and Chemistry
having 30 questions in each part of equal weightage. Each part (subject) has two sections.
(i) Section-A: This section contains 20 multiple choice questions which have only one correct
answer. Each question carries 4 marks for correct answer and –1 mark for wrong answer.
(ii) Section-B: This section contains 10 questions. In Section-B, attempt any five questions out
of 10. The answer to each of the questions is a numerical value. Each question carries 4 marks
for correct answer and –1 mark for wrong answer. For Section-B, the answer should be
rounded off to the nearest integer.
MATHEMATICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer:
1. The number of elements in the set
? ?
? ?
4 2 6
0,2 : 3cos 5cos 2sin 2 0 = ? ? ? ? - ? - ? + = S
is
(1) 10 (2) 8
(3) 12 (4) 9
Answer (4)
Sol. 3cos
4
? – 5cos
2
? – 2sin
6
? + 2 = 0
? cos
2
?[3cos
2
? – 5] – 2sin
6
?
+ 2 = 0
? (1 – sin
2
?) (3 – 3sin
2
? – 5) – 2sin
6
?
+ 2 = 0
? (sin
2
? – 1) (3sin
2
? + 2) – 2sin
6
?
+ 2 = 0
Let sin
2
? = t
(t – 1) (3t + 2) – 2t
3
+ 2 = 0
(t – 1) [3t + 2 – 2 (t
2
+ t + 1)] = 0
(t – 1) [2t
2
– t] = 0
1
0, 1 ,
2
t =
? sin
2
? = 0 ? 3 solution
sin
2
? = 1 ? 2 solution
sin
2
? =
1
2
? 4 solution
? Total solution = 9
2. Let ? ? : 2, 4 ? f be a differentiable function such
that
( ) ( ) ( ) ( ) ( ) log log 1 , [2, 4] ? + + ? ?
ee
x x f x x f x f x x
with ( )
1
2
2
= f and ( )
1
4
2
= f .
Consider the following two statements :
(A) ( ) 1 , for all [2, 4] ?? f x x
(B) ( )
1
, for all [2, 4]
8
?? f x x
Then,
(1) Neither statement (A) nor statement (B) is true
(2) Only statement (B) is true
(3) Both the statements (A) and (B) are true
(4) Only statement (A) is true
Answer (3*)
Sol. f : [2, 4] ? ?
(x log e x) f?(x) + (log e x) f(x) + f(x) ? 1, x ? [2, 4]
? d [x lnx f(x) – x] ? 0 OR d (x lnx ? f(x)) ? 1
? h(x) = x lnx f(x) – x ?
? h(x) ? h(2) , x ? [2, 4]
x lnx f(x) – x ? 2 ln2f(2) – 2
? x lnx f(x) – x ? ln2 – 2, x lnx f(x) – x ? ln4 – 4
So,
ln2 2 1 ln4 4 1
()
ln ln ln ln
fx
x x x x x x
--
+ ? ? +
f(x) ? 1
&
1
()
8
fx ?
Hence both A & B are correct.
But LMVT on f(x) ? x lnx can’t be satisfied. Hence no
such f(x) exist.
3. Let R be a rectangle given by the lines x = 0, x = 2,
y = 0 and y = 5. Let A(?, 0) and B(0, ?), ? ? [0, 2]
and ? ? [0, 5], be such that the line segment AB
divides the area of the rectangle R in the ratio 4 : 1.
Then, the mid-point of AB lies on a
(1) straight line (2) parabola
(3) hyperbola (4) circle
Answer (3)
Sol.
1
10
4
2
20 4
1
1
2
- ??
= ? - ?? = ??
??
4 ? ?? =
Let ,
22
k
h
?
= ? =
? 4hk = 4
? 1 xy =
4. Let
? ?
? ? ? ? , 0, 1, 2 , 1 , 2 ?? = = ? ? ?
??
ij ij
S M a a i j
be a sample space and ? ? : is invertible ? A M S M
be an even. Then P(A) is equal to
(1)
16
27
(2)
47
81
(3)
49
81
(4)
50
81
Answer (4)
Sol. If M is invertible, then |M| ? 0
For |M| = 0
1.
1 1 0 0 2 2
or or
1 1 0 0 2 2
? ? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ? ?
? Total matrix = 3
2. Two 1’s and Two 0’s ? Total matrix = 4
3. Two 2’s and Two 0’s ? Total matrix = 4
4. Two 1’s and Two 2’s ? Total matrix = 4
5. One 1 and three 0’s ? Total matrix = 4
6. One 2 and Three 0’s ? Total matrix = 4
7. One 1 and one 2 and two 0’s ? Total matrix = 8
( )
31 50
1
81 81
PA = - =
5. The number of integral solution x of
2
7
2
7
log 0
23
??
+
??
??
- ??
?
??
-
?? x
x
x
is
(1) 7
(2) 8
(3) 6
(4) 5
Answer (3)
Sol.
2
7
2
7
log 0
23 x
x
x
??
+
??
??
- ??
?
??
-
??
Domain
7
0
2
x+?
–7
2
x ?
7
1
2
x+?
5
2
x
-
?
7
0
23
x
x
-
?
-
x ? 7
3
2
x ?
Domain :
7 5 3
, , 0,
2 2 2
- ? ? ? ?
- ? -
??
??
? ? ? ?
Case I :
7
01
2
x ? + ?
75
22
x - ? ? -
2
7
1
23
x
x
- ??
?
??
-
??
7
11
23
x
x
-
- ? ?
-
7 2 3
0
23
xx
x
- + -
?
-
3 10
0
23
x
x
-
?
-
7 2 3
0
23
xx
x
- - +
?
-
4
0
23
x
x
--
?
-
4
0
23
x
x
+
?
-
No intersection, no solution
Case II :
7
1
2
x+?
5
2
x ?-
2
7
1
23
x
x
- ??
?
??
-
??
7
1
23
x
x
-
?-
-
3 10
,
23
x
??
?
? ?
??
7
1
23
x
x
-
?
-
3
4,
2
x
??
?-
? ?
??
3 3 3 10
, ,
2 2 2 3
x
? ? ? ?
? - ?
? ? ? ?
? ? ? ?
Total 6 integers
6. Let A be a 2 × 2 matrix with real entries such that
'1 AA = ? + , where { 1 , 1} ? ? - - ., If det
2
( ) 4 AA -= , the sum of all possible values of ? is
equal to
(1) 0
(2)
3
2
(3) 2
(4)
5
2
Answer (4)
Sol. Let
ab
A
cd
??
=
??
??
A A I ? = ? +
?
1
1
a c a b
b d c d
? + ? ? ? ? ?
=
? ? ? ?
? ? +
? ? ? ?
1 aa = ? + ?
1
1
a =
-?
.... (i)
bc =? .... (ii)
cb =? .... (iii)
(ii) and (iii) 0 c = or 1 ? = ? (not possible)
? 0 c =
Also
1
1
1
d d d = ? + ? =
-?
? 0, 0 cb ==
2
| | 4 AA -=
| || | 4 A A I -=
22
11
14
11
? ? ? ?
-=
? ? ? ?
- ? - ?
? ? ? ?
?
1
,2
2
?=
7. The value of the integral
2
log 2
2
log 2
log 1
e
x x x
e
e e e dx
-
?? ??
++
?? ??
?? ??
?
is equal to
(1)
( )
2
2 2 5
5
log
2
15
e
??
+
??
-
??
+ ??
??
(2)
( )
2
25
5
log
2
15
e
??
+
??
+
??
+ ??
??
(3)
( )
2 2 5
5
log
2
15
e
??
+
??
-
??
??
+
??
(4)
( )
2
2 3 5
5
log
2
15
e
??
-
??
+
??
+ ??
??
Answer (1)
Page 5
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Morning
Time : 3 hrs. M.M. : 300
IMPORTANT INSTRUCTIONS:
(1) The test is of 3 hours duration.
(2) The Test Booklet consists of 90 questions. The maximum marks are 300.
(3) There are three parts in the question paper consisting of Mathematics, Physics and Chemistry
having 30 questions in each part of equal weightage. Each part (subject) has two sections.
(i) Section-A: This section contains 20 multiple choice questions which have only one correct
answer. Each question carries 4 marks for correct answer and –1 mark for wrong answer.
(ii) Section-B: This section contains 10 questions. In Section-B, attempt any five questions out
of 10. The answer to each of the questions is a numerical value. Each question carries 4 marks
for correct answer and –1 mark for wrong answer. For Section-B, the answer should be
rounded off to the nearest integer.
MATHEMATICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer:
1. The number of elements in the set
? ?
? ?
4 2 6
0,2 : 3cos 5cos 2sin 2 0 = ? ? ? ? - ? - ? + = S
is
(1) 10 (2) 8
(3) 12 (4) 9
Answer (4)
Sol. 3cos
4
? – 5cos
2
? – 2sin
6
? + 2 = 0
? cos
2
?[3cos
2
? – 5] – 2sin
6
?
+ 2 = 0
? (1 – sin
2
?) (3 – 3sin
2
? – 5) – 2sin
6
?
+ 2 = 0
? (sin
2
? – 1) (3sin
2
? + 2) – 2sin
6
?
+ 2 = 0
Let sin
2
? = t
(t – 1) (3t + 2) – 2t
3
+ 2 = 0
(t – 1) [3t + 2 – 2 (t
2
+ t + 1)] = 0
(t – 1) [2t
2
– t] = 0
1
0, 1 ,
2
t =
? sin
2
? = 0 ? 3 solution
sin
2
? = 1 ? 2 solution
sin
2
? =
1
2
? 4 solution
? Total solution = 9
2. Let ? ? : 2, 4 ? f be a differentiable function such
that
( ) ( ) ( ) ( ) ( ) log log 1 , [2, 4] ? + + ? ?
ee
x x f x x f x f x x
with ( )
1
2
2
= f and ( )
1
4
2
= f .
Consider the following two statements :
(A) ( ) 1 , for all [2, 4] ?? f x x
(B) ( )
1
, for all [2, 4]
8
?? f x x
Then,
(1) Neither statement (A) nor statement (B) is true
(2) Only statement (B) is true
(3) Both the statements (A) and (B) are true
(4) Only statement (A) is true
Answer (3*)
Sol. f : [2, 4] ? ?
(x log e x) f?(x) + (log e x) f(x) + f(x) ? 1, x ? [2, 4]
? d [x lnx f(x) – x] ? 0 OR d (x lnx ? f(x)) ? 1
? h(x) = x lnx f(x) – x ?
? h(x) ? h(2) , x ? [2, 4]
x lnx f(x) – x ? 2 ln2f(2) – 2
? x lnx f(x) – x ? ln2 – 2, x lnx f(x) – x ? ln4 – 4
So,
ln2 2 1 ln4 4 1
()
ln ln ln ln
fx
x x x x x x
--
+ ? ? +
f(x) ? 1
&
1
()
8
fx ?
Hence both A & B are correct.
But LMVT on f(x) ? x lnx can’t be satisfied. Hence no
such f(x) exist.
3. Let R be a rectangle given by the lines x = 0, x = 2,
y = 0 and y = 5. Let A(?, 0) and B(0, ?), ? ? [0, 2]
and ? ? [0, 5], be such that the line segment AB
divides the area of the rectangle R in the ratio 4 : 1.
Then, the mid-point of AB lies on a
(1) straight line (2) parabola
(3) hyperbola (4) circle
Answer (3)
Sol.
1
10
4
2
20 4
1
1
2
- ??
= ? - ?? = ??
??
4 ? ?? =
Let ,
22
k
h
?
= ? =
? 4hk = 4
? 1 xy =
4. Let
? ?
? ? ? ? , 0, 1, 2 , 1 , 2 ?? = = ? ? ?
??
ij ij
S M a a i j
be a sample space and ? ? : is invertible ? A M S M
be an even. Then P(A) is equal to
(1)
16
27
(2)
47
81
(3)
49
81
(4)
50
81
Answer (4)
Sol. If M is invertible, then |M| ? 0
For |M| = 0
1.
1 1 0 0 2 2
or or
1 1 0 0 2 2
? ? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ? ?
? Total matrix = 3
2. Two 1’s and Two 0’s ? Total matrix = 4
3. Two 2’s and Two 0’s ? Total matrix = 4
4. Two 1’s and Two 2’s ? Total matrix = 4
5. One 1 and three 0’s ? Total matrix = 4
6. One 2 and Three 0’s ? Total matrix = 4
7. One 1 and one 2 and two 0’s ? Total matrix = 8
( )
31 50
1
81 81
PA = - =
5. The number of integral solution x of
2
7
2
7
log 0
23
??
+
??
??
- ??
?
??
-
?? x
x
x
is
(1) 7
(2) 8
(3) 6
(4) 5
Answer (3)
Sol.
2
7
2
7
log 0
23 x
x
x
??
+
??
??
- ??
?
??
-
??
Domain
7
0
2
x+?
–7
2
x ?
7
1
2
x+?
5
2
x
-
?
7
0
23
x
x
-
?
-
x ? 7
3
2
x ?
Domain :
7 5 3
, , 0,
2 2 2
- ? ? ? ?
- ? -
??
??
? ? ? ?
Case I :
7
01
2
x ? + ?
75
22
x - ? ? -
2
7
1
23
x
x
- ??
?
??
-
??
7
11
23
x
x
-
- ? ?
-
7 2 3
0
23
xx
x
- + -
?
-
3 10
0
23
x
x
-
?
-
7 2 3
0
23
xx
x
- - +
?
-
4
0
23
x
x
--
?
-
4
0
23
x
x
+
?
-
No intersection, no solution
Case II :
7
1
2
x+?
5
2
x ?-
2
7
1
23
x
x
- ??
?
??
-
??
7
1
23
x
x
-
?-
-
3 10
,
23
x
??
?
? ?
??
7
1
23
x
x
-
?
-
3
4,
2
x
??
?-
? ?
??
3 3 3 10
, ,
2 2 2 3
x
? ? ? ?
? - ?
? ? ? ?
? ? ? ?
Total 6 integers
6. Let A be a 2 × 2 matrix with real entries such that
'1 AA = ? + , where { 1 , 1} ? ? - - ., If det
2
( ) 4 AA -= , the sum of all possible values of ? is
equal to
(1) 0
(2)
3
2
(3) 2
(4)
5
2
Answer (4)
Sol. Let
ab
A
cd
??
=
??
??
A A I ? = ? +
?
1
1
a c a b
b d c d
? + ? ? ? ? ?
=
? ? ? ?
? ? +
? ? ? ?
1 aa = ? + ?
1
1
a =
-?
.... (i)
bc =? .... (ii)
cb =? .... (iii)
(ii) and (iii) 0 c = or 1 ? = ? (not possible)
? 0 c =
Also
1
1
1
d d d = ? + ? =
-?
? 0, 0 cb ==
2
| | 4 AA -=
| || | 4 A A I -=
22
11
14
11
? ? ? ?
-=
? ? ? ?
- ? - ?
? ? ? ?
?
1
,2
2
?=
7. The value of the integral
2
log 2
2
log 2
log 1
e
x x x
e
e e e dx
-
?? ??
++
?? ??
?? ??
?
is equal to
(1)
( )
2
2 2 5
5
log
2
15
e
??
+
??
-
??
+ ??
??
(2)
( )
2
25
5
log
2
15
e
??
+
??
+
??
+ ??
??
(3)
( )
2 2 5
5
log
2
15
e
??
+
??
-
??
??
+
??
(4)
( )
2
2 3 5
5
log
2
15
e
??
-
??
+
??
+ ??
??
Answer (1)
Sol.
log 2
2
log 2
log 1
e
e
x x x
e
I e e e dx
-
??
??
= + +
??
??
??
??
?
Put
x
et =
x
e dx dt =
2
2
I
1
II
2
1 log 1
e
I t t dt
??
= ? + +
??
??
?
2
2
2
1
2
1/2
2
ln( 1 )
1
t
t t x dt
t
??
= + + -
??
??
+
?
2
22
1
2
ln 1 1 t t t t
??
= + + - +
??
??
1 5 1 5
2ln 5 2 5 ln
2 2 2 2
??
??
= + - - + -
??
??
??
??
2
2(2 5) 5
ln
2
15
??
+
??
=-
??
+
??
8. Let sets A and B have 5 elements each. Let the
mean of the elements in sets A and B 5 and 8
respectively and the variance of the elements in
sets A and B be 12 and 20 respectively. A new set
C of 10 elements is formed by subtracting 3 from
each element of A and adding 2 to each element of
B. Then the sum of the mean and variance of the
elements of C is ______ .
(1) 40 (2) 32
(3) 38 (4) 36
Answer (3)
Sol. A
1 2 5
mean ( , .... ) 5 x x x =
1 2 5
( 3, 3.... 3) 2 x x x ? - - - =
1 2 5
Var( , ,.... ) 12 x x x =
1 2 5
Var( 3, 3,.... 3) 12 x x x - - - =
2
( 3)
4 12
5
i
x -
-=
?
B
1 2 5
mean( , .... ) 8 y y y =
1 2 5
mean( 2, 2,.... 2) 10 y y y ? + + + =
1 2 5
Var( , .... ) 20 y y y =
1 2 5
Var( 2, 2.... 2) 20 y y y + + + =
2
1
( 2)
100 20
5
y +
-=
?
Combined mean
5
1
( 3) ( 2)
10
ii
i
xy
=
- + +
??
10 50
6
10
+
==
Combined variance
2
22
( 3) ( 2) 6
10
ii
xy - + + -
=
??
80 120 5
36 32
10
+?
= - =
9. Let ( , , ) ? ? ? be the image of point P (2,3,5) in the
plane 2 3 6 x y z + - = . Then ? + ? + ? is equal to
(1) 5 (2) 10
(3) 12 (4) 9
Answer (2)
Sol.
2 3 5
2 1 3
? - ? - ? -
==
-
(4 3 15 6)
22
14
+ - -
= - =
?
2
2
2
?-
= ? 6 ?=
3
2
1
?-
= ? 5 ?=
5
2
3
?-
=
-
? 1 ? = -
? 6 5 1 10 ? + ? + ? = + - =
Option (2) is correct.
10. Let
2
( ) – [ ] f x x x x x
??
= - + +
??
, where x ? and [t]
denotes the greatest integer less than or equal to t.
Then, f is
(1) continuous at x = 0, but not continuous at x = 1
(2) continuous at x = 1, but not continuous at x = 0
(3) continuous at x = 0 and x = 1
(4) not continuous at x = 0 and x = 1
Answer (2)
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