Page 1
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Evening
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
Evening
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 domain of the function
( )
? ? ? ?
2
1
3 10
=
--
fx
xx
is (where [x] denotes the
greatest integer less than or equal to x)
(1) ( –?, –3] ? (5, ?) (2) ( –?, –2) ? [6, ?)
(3) ( –?, –2) ? (5, ?) (4) ( –?, –3] ? [6, ?)
Answer (2)
Sol. ( )
? ? ? ?
2
1
3 10
fx
xx
=
--
For Domain [x]
2
– 3[x] – 10 > 0
? ([x] – 5) ([x] + 2) > 0
? [x] ?( –?, –2) ? (5, ?)
? x ?( –?, –2) ? [6, ?)
2. If the system of linear equations
7x + 11y + ?z = 13
5x + 4y + 7z = ?
175x + 194y + 57z = 361
has infinitely many solutions, then ? + ? + 2 is equal
to
(1) 4 (2) 3
(3) 5 (4) 6
Answer (1)
Sol. 7x + 11y + ?z = 13
5x + 4y + 7z = ?
175x + 194y + 57z = 361
For infinite solution,
7 11
5 4 7 0
175 194 57
?
=
?
7 11
5 4 7 0
0 81 57 25
?
=
- - ?
? 81(49 – 5?) + (57 – 25?) ( –27) = 0
? 270? = –2430 ? –9 ?=
and ?1 = 0
1 3 1 1 – 9
4 7 0
361 194 57
?=
? 11 ?=
? ? + ? + 2 = 4
3. Let A = {1, 3, 4, 6, 9} and B = {2, 4, 5, 8, 10}. Let R
be a relation defined on A × B such that R = {((a1,
b1), (a2, b2)) : a1 ? b2 and b1 ? a2}. Then the number
of elements in the set R is
(1) 160 (2) 52
(3) 26 (4) 180
Answer (1)
Sol. ? ? ? ? 1 , 3, 4, 6, 9 2, 4, 5, 8, 10 AB ==
( ) ( ) ( ) ? ?
1 1 2 2 1 2 1 2
, , , : and R a b a b a b b a = ? ?
For Similarly for (b1, a2) we
will have
a1 = 1 b2 ? 5 b1 ? 2 a2 = 4
a1 = 3 b2 ? 4 b1 ? 4 a2 = 3
a1 = 4 b2 ? 4 b1 ? 5 a2 = 2
a1 = 6 b2 ? 2 b1 ? 8 a2 = 1
a1 = 9 b2 ? 1 b1 ? 10 a2 = 0
16 cases 10 cases
? Total elements in relation = 16 × 10 = 160
4. Let the mean of 6 observations 1, 2, 4, 5, x and y
be 5 and their variance be 10. Then their mean
deviation about the mean is equal to
(1)
7
3
(2) 3
(3)
8
3
(4)
10
3
Answer (3)
Page 3
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Evening
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 domain of the function
( )
? ? ? ?
2
1
3 10
=
--
fx
xx
is (where [x] denotes the
greatest integer less than or equal to x)
(1) ( –?, –3] ? (5, ?) (2) ( –?, –2) ? [6, ?)
(3) ( –?, –2) ? (5, ?) (4) ( –?, –3] ? [6, ?)
Answer (2)
Sol. ( )
? ? ? ?
2
1
3 10
fx
xx
=
--
For Domain [x]
2
– 3[x] – 10 > 0
? ([x] – 5) ([x] + 2) > 0
? [x] ?( –?, –2) ? (5, ?)
? x ?( –?, –2) ? [6, ?)
2. If the system of linear equations
7x + 11y + ?z = 13
5x + 4y + 7z = ?
175x + 194y + 57z = 361
has infinitely many solutions, then ? + ? + 2 is equal
to
(1) 4 (2) 3
(3) 5 (4) 6
Answer (1)
Sol. 7x + 11y + ?z = 13
5x + 4y + 7z = ?
175x + 194y + 57z = 361
For infinite solution,
7 11
5 4 7 0
175 194 57
?
=
?
7 11
5 4 7 0
0 81 57 25
?
=
- - ?
? 81(49 – 5?) + (57 – 25?) ( –27) = 0
? 270? = –2430 ? –9 ?=
and ?1 = 0
1 3 1 1 – 9
4 7 0
361 194 57
?=
? 11 ?=
? ? + ? + 2 = 4
3. Let A = {1, 3, 4, 6, 9} and B = {2, 4, 5, 8, 10}. Let R
be a relation defined on A × B such that R = {((a1,
b1), (a2, b2)) : a1 ? b2 and b1 ? a2}. Then the number
of elements in the set R is
(1) 160 (2) 52
(3) 26 (4) 180
Answer (1)
Sol. ? ? ? ? 1 , 3, 4, 6, 9 2, 4, 5, 8, 10 AB ==
( ) ( ) ( ) ? ?
1 1 2 2 1 2 1 2
, , , : and R a b a b a b b a = ? ?
For Similarly for (b1, a2) we
will have
a1 = 1 b2 ? 5 b1 ? 2 a2 = 4
a1 = 3 b2 ? 4 b1 ? 4 a2 = 3
a1 = 4 b2 ? 4 b1 ? 5 a2 = 2
a1 = 6 b2 ? 2 b1 ? 8 a2 = 1
a1 = 9 b2 ? 1 b1 ? 10 a2 = 0
16 cases 10 cases
? Total elements in relation = 16 × 10 = 160
4. Let the mean of 6 observations 1, 2, 4, 5, x and y
be 5 and their variance be 10. Then their mean
deviation about the mean is equal to
(1)
7
3
(2) 3
(3)
8
3
(4)
10
3
Answer (3)
Sol. 12 + x + y = 30
? x + y = 18
and
22
46
25 10
6
xy ++
-=
? x = 10, y = 8
Now, mean deviation about mean
4 3 1 0 5 3 8
63
+ + + + +
==
5. If four distinct points with position vectors
, , and a b c d are coplanar, then
??
??
a b c is equal
to
(1)
? ? ? ? ? ?
++
? ? ? ? ? ?
d b a a c d d b c
(2)
? ? ? ? ? ?
++
? ? ? ? ? ?
a d b d c a d b c
(3)
? ?
? ? ? ?
++
? ? ? ?
d c a b d a c d b
(4)
? ?
c
? ? ? ?
++
? ? ? ?
b c d d a d b a
Answer (3)
Sol. 0 b a c a d a
??
- - - =
??
( ) ( ) ( )
0 b a c a d a
??
- ? - ? - =
??
( ) ( )
0 b a c d c a a d - ? ? - ? - ? =
0 b c d b c a b a d a c d
? ? ? ? ? ? ? ?
- - - =
? ? ? ? ? ? ? ?
? a b c b c d a b d a d c
? ? ? ? ? ? ? ?
= + +
? ? ? ? ? ? ? ?
d c a b d a c d b
? ? ? ? ? ?
= + +
? ? ? ? ? ?
6. Let () y y x = be the solution of the differential
equation
( )
2
5
57
1
5
,0
( 1)
x
dy
yx
dx
x x x
+
+ = ?
+
. If (1) 2, y = then
(2) y is equal to
(1)
637
128
(2)
679
128
(3)
693
128
(4)
697
128
Answer (3)
Sol. I.F. =
5
5
(1 )
dx
xx
e
+
?
=
6
5
5
1
1
dx
x
x
e
??
+
??
??
?
Put
5
1
1 t
x
+=
6
5
dx dt
x
-
=
5
ln
5
1
1
dt
t
t
x
ee
t
x
-
-
?
= = =
+
5 5 5 2
5 5 7
(1 )
11
x x x
y dx c
x x x
??
+
=+ ??
??
++
??
?
54
5
1
4
1
xx
yc
x
x
??
-
= + + ??
??
+
??
Now (1) 2 y = , then
7
4
c =
?
693
(2)
128
y =
7. Let P be the plane passing through the points (5, 3,
0), (13, 3, –2) and (1, 6, 2). For ?? , if the
distances of the points A (3,4, ) ? and B (2, , ) a ? from
the plane P are 2 and 3 respectively, then the
positive value of a is
(1) 6 (2) 3
(3) 5 (4) 4
Answer (4)
Sol.
ˆˆ
82 AB i k =-
ˆ ˆ ˆ
4 3 2 AC i j k = - + +
ˆ ˆ ˆ
8 0 2
4 3 2
i j k
AB AC ? = -
-
ˆ ˆ ˆ
6 8 24 i j k = - +
Page 4
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Evening
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 domain of the function
( )
? ? ? ?
2
1
3 10
=
--
fx
xx
is (where [x] denotes the
greatest integer less than or equal to x)
(1) ( –?, –3] ? (5, ?) (2) ( –?, –2) ? [6, ?)
(3) ( –?, –2) ? (5, ?) (4) ( –?, –3] ? [6, ?)
Answer (2)
Sol. ( )
? ? ? ?
2
1
3 10
fx
xx
=
--
For Domain [x]
2
– 3[x] – 10 > 0
? ([x] – 5) ([x] + 2) > 0
? [x] ?( –?, –2) ? (5, ?)
? x ?( –?, –2) ? [6, ?)
2. If the system of linear equations
7x + 11y + ?z = 13
5x + 4y + 7z = ?
175x + 194y + 57z = 361
has infinitely many solutions, then ? + ? + 2 is equal
to
(1) 4 (2) 3
(3) 5 (4) 6
Answer (1)
Sol. 7x + 11y + ?z = 13
5x + 4y + 7z = ?
175x + 194y + 57z = 361
For infinite solution,
7 11
5 4 7 0
175 194 57
?
=
?
7 11
5 4 7 0
0 81 57 25
?
=
- - ?
? 81(49 – 5?) + (57 – 25?) ( –27) = 0
? 270? = –2430 ? –9 ?=
and ?1 = 0
1 3 1 1 – 9
4 7 0
361 194 57
?=
? 11 ?=
? ? + ? + 2 = 4
3. Let A = {1, 3, 4, 6, 9} and B = {2, 4, 5, 8, 10}. Let R
be a relation defined on A × B such that R = {((a1,
b1), (a2, b2)) : a1 ? b2 and b1 ? a2}. Then the number
of elements in the set R is
(1) 160 (2) 52
(3) 26 (4) 180
Answer (1)
Sol. ? ? ? ? 1 , 3, 4, 6, 9 2, 4, 5, 8, 10 AB ==
( ) ( ) ( ) ? ?
1 1 2 2 1 2 1 2
, , , : and R a b a b a b b a = ? ?
For Similarly for (b1, a2) we
will have
a1 = 1 b2 ? 5 b1 ? 2 a2 = 4
a1 = 3 b2 ? 4 b1 ? 4 a2 = 3
a1 = 4 b2 ? 4 b1 ? 5 a2 = 2
a1 = 6 b2 ? 2 b1 ? 8 a2 = 1
a1 = 9 b2 ? 1 b1 ? 10 a2 = 0
16 cases 10 cases
? Total elements in relation = 16 × 10 = 160
4. Let the mean of 6 observations 1, 2, 4, 5, x and y
be 5 and their variance be 10. Then their mean
deviation about the mean is equal to
(1)
7
3
(2) 3
(3)
8
3
(4)
10
3
Answer (3)
Sol. 12 + x + y = 30
? x + y = 18
and
22
46
25 10
6
xy ++
-=
? x = 10, y = 8
Now, mean deviation about mean
4 3 1 0 5 3 8
63
+ + + + +
==
5. If four distinct points with position vectors
, , and a b c d are coplanar, then
??
??
a b c is equal
to
(1)
? ? ? ? ? ?
++
? ? ? ? ? ?
d b a a c d d b c
(2)
? ? ? ? ? ?
++
? ? ? ? ? ?
a d b d c a d b c
(3)
? ?
? ? ? ?
++
? ? ? ?
d c a b d a c d b
(4)
? ?
c
? ? ? ?
++
? ? ? ?
b c d d a d b a
Answer (3)
Sol. 0 b a c a d a
??
- - - =
??
( ) ( ) ( )
0 b a c a d a
??
- ? - ? - =
??
( ) ( )
0 b a c d c a a d - ? ? - ? - ? =
0 b c d b c a b a d a c d
? ? ? ? ? ? ? ?
- - - =
? ? ? ? ? ? ? ?
? a b c b c d a b d a d c
? ? ? ? ? ? ? ?
= + +
? ? ? ? ? ? ? ?
d c a b d a c d b
? ? ? ? ? ?
= + +
? ? ? ? ? ?
6. Let () y y x = be the solution of the differential
equation
( )
2
5
57
1
5
,0
( 1)
x
dy
yx
dx
x x x
+
+ = ?
+
. If (1) 2, y = then
(2) y is equal to
(1)
637
128
(2)
679
128
(3)
693
128
(4)
697
128
Answer (3)
Sol. I.F. =
5
5
(1 )
dx
xx
e
+
?
=
6
5
5
1
1
dx
x
x
e
??
+
??
??
?
Put
5
1
1 t
x
+=
6
5
dx dt
x
-
=
5
ln
5
1
1
dt
t
t
x
ee
t
x
-
-
?
= = =
+
5 5 5 2
5 5 7
(1 )
11
x x x
y dx c
x x x
??
+
=+ ??
??
++
??
?
54
5
1
4
1
xx
yc
x
x
??
-
= + + ??
??
+
??
Now (1) 2 y = , then
7
4
c =
?
693
(2)
128
y =
7. Let P be the plane passing through the points (5, 3,
0), (13, 3, –2) and (1, 6, 2). For ?? , if the
distances of the points A (3,4, ) ? and B (2, , ) a ? from
the plane P are 2 and 3 respectively, then the
positive value of a is
(1) 6 (2) 3
(3) 5 (4) 4
Answer (4)
Sol.
ˆˆ
82 AB i k =-
ˆ ˆ ˆ
4 3 2 AC i j k = - + +
ˆ ˆ ˆ
8 0 2
4 3 2
i j k
AB AC ? = -
-
ˆ ˆ ˆ
6 8 24 i j k = - +
Equation of plane : 6x – 8y + 24z = d passes
through (5, 3, 0)
6 × 5 – 8 × 3 + 24 × 0 = d
d = 6
6x – 8y + 24z = 6 ? 3x – 4y + 12z = 3
Distance of point (3, 4, ?)
9 16 12 3
23
9 16 144
- + ? -
= ? ? =
++
Distance of point (2, ?, a)
3 2 4 3 12 3
3
13
a ? - ? + ? -
=
12a – 9 = 39
12a = 48
a = 4
8. The converse of ((~ ) ) p q r ?? is
(1) ((~ ) ) p q r ?? (2) (~ ) r p q ??
(3) (~ ) ((~ ) ) r p q ?? (4) ( (~ )) (~ ) p q r ??
Answer (4)
Sol. Converse of (?p ? q) ? r is
r ? (~p ? q)
(p ? (~q)) ? (~r)
9. Let the function
? ?
: 0, 2 ? f be defined as
? ?
2
min , [ ]
log ,
, [0, 1)
()
[1 , 2]
e
x x x
xx
ex
fx
ex
-
-??
??
?
?
?
=
?
?
?
?
where [t] denotes the greatest integer less than or
equal to t. Then the value of the integral
2
0
() xf x dx
?
is
(1)
3
1
2
e
+ (2)
2
1
( 1)
2
ee
??
-+
??
??
(3) 21 e - (4)
1
2
2
e -
Answer (4)
Sol.
? ?
2
min ,
[0, 1)
()
[1 , 2]
xx
ex
fx
ex
?
?
?
=
?
?
?
?
2
[0, 1)
[1 , 2]
x
ex
ex
?
?
?
=
?
? ?
?
ln [1 , 2) xx -? for [1 , 2] x ?
? [ ln ] 1 xx -=
2
2 1 2
0 0 1
( ) . .
x
x f x x e dx x edx =+
? ? ?
2
xt = ? 2xdx dt =
2
1
2
0
1
1
22
t
x
e dt e =+
?
?
13
22
ee - ??
+
??
??
?
1
2
2
e -
Option (4) is correct.
10. If : f ? be a continuous function satisfying
24
00
(sin2 )sin (cos2 )cos 0 f x xdx f x x dx
??
+ ? =
??
, then
the value of ? is
(1) 2 (2) 3 -
(3) 3 (4) 2 -
Answer (4)
Sol.
24
00
(sin2 )sin (cos2 ).cos 0 f x xdx f x xdx
??
+ ? =
??
Let
2
0
(sin2 ).sin I f x xdx
?
=
?
42
0
4
(sin2 )sin (sin2 ).sin f x xdx f x xdx
??
?
=+
??
4
0
(cos2 )sin
4
f x x dx
?
???
=-
??
??
?
4
0
sin2 sin
44
f x x dx
?
?? ?? ? ? ? ?
+ + +
??
? ? ? ?
? ? ? ? ??
?
4
0
11
(cos2 ) cos sin
22
f x x x dx
?
??
=-
??
??
?
Page 5
Answers & Solutions
for
JEE (Main)-2023 (Online) Phase-2
(Mathematics, Physics and Chemistry)
11/04/2023
Evening
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 domain of the function
( )
? ? ? ?
2
1
3 10
=
--
fx
xx
is (where [x] denotes the
greatest integer less than or equal to x)
(1) ( –?, –3] ? (5, ?) (2) ( –?, –2) ? [6, ?)
(3) ( –?, –2) ? (5, ?) (4) ( –?, –3] ? [6, ?)
Answer (2)
Sol. ( )
? ? ? ?
2
1
3 10
fx
xx
=
--
For Domain [x]
2
– 3[x] – 10 > 0
? ([x] – 5) ([x] + 2) > 0
? [x] ?( –?, –2) ? (5, ?)
? x ?( –?, –2) ? [6, ?)
2. If the system of linear equations
7x + 11y + ?z = 13
5x + 4y + 7z = ?
175x + 194y + 57z = 361
has infinitely many solutions, then ? + ? + 2 is equal
to
(1) 4 (2) 3
(3) 5 (4) 6
Answer (1)
Sol. 7x + 11y + ?z = 13
5x + 4y + 7z = ?
175x + 194y + 57z = 361
For infinite solution,
7 11
5 4 7 0
175 194 57
?
=
?
7 11
5 4 7 0
0 81 57 25
?
=
- - ?
? 81(49 – 5?) + (57 – 25?) ( –27) = 0
? 270? = –2430 ? –9 ?=
and ?1 = 0
1 3 1 1 – 9
4 7 0
361 194 57
?=
? 11 ?=
? ? + ? + 2 = 4
3. Let A = {1, 3, 4, 6, 9} and B = {2, 4, 5, 8, 10}. Let R
be a relation defined on A × B such that R = {((a1,
b1), (a2, b2)) : a1 ? b2 and b1 ? a2}. Then the number
of elements in the set R is
(1) 160 (2) 52
(3) 26 (4) 180
Answer (1)
Sol. ? ? ? ? 1 , 3, 4, 6, 9 2, 4, 5, 8, 10 AB ==
( ) ( ) ( ) ? ?
1 1 2 2 1 2 1 2
, , , : and R a b a b a b b a = ? ?
For Similarly for (b1, a2) we
will have
a1 = 1 b2 ? 5 b1 ? 2 a2 = 4
a1 = 3 b2 ? 4 b1 ? 4 a2 = 3
a1 = 4 b2 ? 4 b1 ? 5 a2 = 2
a1 = 6 b2 ? 2 b1 ? 8 a2 = 1
a1 = 9 b2 ? 1 b1 ? 10 a2 = 0
16 cases 10 cases
? Total elements in relation = 16 × 10 = 160
4. Let the mean of 6 observations 1, 2, 4, 5, x and y
be 5 and their variance be 10. Then their mean
deviation about the mean is equal to
(1)
7
3
(2) 3
(3)
8
3
(4)
10
3
Answer (3)
Sol. 12 + x + y = 30
? x + y = 18
and
22
46
25 10
6
xy ++
-=
? x = 10, y = 8
Now, mean deviation about mean
4 3 1 0 5 3 8
63
+ + + + +
==
5. If four distinct points with position vectors
, , and a b c d are coplanar, then
??
??
a b c is equal
to
(1)
? ? ? ? ? ?
++
? ? ? ? ? ?
d b a a c d d b c
(2)
? ? ? ? ? ?
++
? ? ? ? ? ?
a d b d c a d b c
(3)
? ?
? ? ? ?
++
? ? ? ?
d c a b d a c d b
(4)
? ?
c
? ? ? ?
++
? ? ? ?
b c d d a d b a
Answer (3)
Sol. 0 b a c a d a
??
- - - =
??
( ) ( ) ( )
0 b a c a d a
??
- ? - ? - =
??
( ) ( )
0 b a c d c a a d - ? ? - ? - ? =
0 b c d b c a b a d a c d
? ? ? ? ? ? ? ?
- - - =
? ? ? ? ? ? ? ?
? a b c b c d a b d a d c
? ? ? ? ? ? ? ?
= + +
? ? ? ? ? ? ? ?
d c a b d a c d b
? ? ? ? ? ?
= + +
? ? ? ? ? ?
6. Let () y y x = be the solution of the differential
equation
( )
2
5
57
1
5
,0
( 1)
x
dy
yx
dx
x x x
+
+ = ?
+
. If (1) 2, y = then
(2) y is equal to
(1)
637
128
(2)
679
128
(3)
693
128
(4)
697
128
Answer (3)
Sol. I.F. =
5
5
(1 )
dx
xx
e
+
?
=
6
5
5
1
1
dx
x
x
e
??
+
??
??
?
Put
5
1
1 t
x
+=
6
5
dx dt
x
-
=
5
ln
5
1
1
dt
t
t
x
ee
t
x
-
-
?
= = =
+
5 5 5 2
5 5 7
(1 )
11
x x x
y dx c
x x x
??
+
=+ ??
??
++
??
?
54
5
1
4
1
xx
yc
x
x
??
-
= + + ??
??
+
??
Now (1) 2 y = , then
7
4
c =
?
693
(2)
128
y =
7. Let P be the plane passing through the points (5, 3,
0), (13, 3, –2) and (1, 6, 2). For ?? , if the
distances of the points A (3,4, ) ? and B (2, , ) a ? from
the plane P are 2 and 3 respectively, then the
positive value of a is
(1) 6 (2) 3
(3) 5 (4) 4
Answer (4)
Sol.
ˆˆ
82 AB i k =-
ˆ ˆ ˆ
4 3 2 AC i j k = - + +
ˆ ˆ ˆ
8 0 2
4 3 2
i j k
AB AC ? = -
-
ˆ ˆ ˆ
6 8 24 i j k = - +
Equation of plane : 6x – 8y + 24z = d passes
through (5, 3, 0)
6 × 5 – 8 × 3 + 24 × 0 = d
d = 6
6x – 8y + 24z = 6 ? 3x – 4y + 12z = 3
Distance of point (3, 4, ?)
9 16 12 3
23
9 16 144
- + ? -
= ? ? =
++
Distance of point (2, ?, a)
3 2 4 3 12 3
3
13
a ? - ? + ? -
=
12a – 9 = 39
12a = 48
a = 4
8. The converse of ((~ ) ) p q r ?? is
(1) ((~ ) ) p q r ?? (2) (~ ) r p q ??
(3) (~ ) ((~ ) ) r p q ?? (4) ( (~ )) (~ ) p q r ??
Answer (4)
Sol. Converse of (?p ? q) ? r is
r ? (~p ? q)
(p ? (~q)) ? (~r)
9. Let the function
? ?
: 0, 2 ? f be defined as
? ?
2
min , [ ]
log ,
, [0, 1)
()
[1 , 2]
e
x x x
xx
ex
fx
ex
-
-??
??
?
?
?
=
?
?
?
?
where [t] denotes the greatest integer less than or
equal to t. Then the value of the integral
2
0
() xf x dx
?
is
(1)
3
1
2
e
+ (2)
2
1
( 1)
2
ee
??
-+
??
??
(3) 21 e - (4)
1
2
2
e -
Answer (4)
Sol.
? ?
2
min ,
[0, 1)
()
[1 , 2]
xx
ex
fx
ex
?
?
?
=
?
?
?
?
2
[0, 1)
[1 , 2]
x
ex
ex
?
?
?
=
?
? ?
?
ln [1 , 2) xx -? for [1 , 2] x ?
? [ ln ] 1 xx -=
2
2 1 2
0 0 1
( ) . .
x
x f x x e dx x edx =+
? ? ?
2
xt = ? 2xdx dt =
2
1
2
0
1
1
22
t
x
e dt e =+
?
?
13
22
ee - ??
+
??
??
?
1
2
2
e -
Option (4) is correct.
10. If : f ? be a continuous function satisfying
24
00
(sin2 )sin (cos2 )cos 0 f x xdx f x x dx
??
+ ? =
??
, then
the value of ? is
(1) 2 (2) 3 -
(3) 3 (4) 2 -
Answer (4)
Sol.
24
00
(sin2 )sin (cos2 ).cos 0 f x xdx f x xdx
??
+ ? =
??
Let
2
0
(sin2 ).sin I f x xdx
?
=
?
42
0
4
(sin2 )sin (sin2 ).sin f x xdx f x xdx
??
?
=+
??
4
0
(cos2 )sin
4
f x x dx
?
???
=-
??
??
?
4
0
sin2 sin
44
f x x dx
?
?? ?? ? ? ? ?
+ + +
??
? ? ? ?
? ? ? ? ??
?
4
0
11
(cos2 ) cos sin
22
f x x x dx
?
??
=-
??
??
?
4
0
11
(cos2 ) cos sin
22
f x x x dx
?
??
++
??
??
?
4
0
(cos2 )( 2 cos ) f x x dx
?
=
?
? 2 ? = -
Option (4) is correct.
11. If the radius of the largest circle with centre (2, 0)
inscribed in the ellipse x
2
+ 4y
2
= 36 is r, then 12r
2
is equal to
(1) 115 (2) 92
(3) 69 (4) 72
Answer (2)
Sol. Equation of normal at P (6cos?, 3sin?) is
6sec 3cos 27 x ec y
If passes through (2, 0)
? 12sec? = 27
?
4 65
cos , sin
99
8 65
,
33
P
r = OP (O = (2, 0))
=
2
2
8 65
2
33
=
69
3
?
2
69
12 12 92
9
r
? Option (2) is correct.
12. Let the line passing through the points P(2, –1, 2)
and Q(5, 3, 4) meet the plane x – y + z = 4 at the
point R. Then the distance of the point R from the
plane x + 2y + 3z + 2 = 0 measured parallel to the
line
7 3 2
2 2 1
- + -
==
x y z
is
(1) 61 (2) 189
(3) 31 (4) 3
Answer (4)
Sol. Equation of line PQ.
2 1 2
3 4 2
x y z
Let R be (3? + 2, 4? – 1, 2? + 2)
R lies on plane x – y + z = 4
? 3? + 2 – 4? + 1 + 2? + 2 = 4
? ? = –1
? R( –1, –5, 0)
Let SR be :
15
2 2 1
x y z
k
S : (2k – 1, 2k – 5, k)
S lies on plane : x + 2y + 3z + 2 = 0
? (2k – 1) + (4k – 10) + 3k + 2 = 0
? 9k – 9 = 0 ? k = 1
S(1, –3, 1) ? 4 4 1 3 SR
? Option (4) is correct.
13. If ( )
2
1
9
103 81 ,
8
x x x
x x x x
x x x
+
+ ? = +
+?
then ,
3
?
?
are the roots of the equation
(1) 4x
2
+ 24x – 27 = 0 (2) 4x
2
– 24x – 27 = 0
(3) 4x
2
+ 24x + 27 = 0 (4) 4x
2
– 24x + 27 = 0
Answer (4)
Sol. ( )
2
1
9
103 81
8
x x x
x x x x
x x x
+
+ ? = +
+?
Put x = 0
2
1 0 0
9
0 0 81
8
00
6
3
3
3
2
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