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 Page 1


                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 1  
Date: 8
th
 January 2020 (Shift 1) 
Time: 9:30 A.M. to 12:30 P.M. 
Subject: Mathematics 
 
 
1. The maximum values of ?? 
19
?? , ?? 
20
?? , ?? 
21
?? are ?? ,?? ,?? respectively. Then, the relation 
between ?? ,?? ,?? is 
a. 
?? 22
=
?? 42
=
?? 11
 b. 
?? 11
=
?? 22
=
?? 42
 
c. 
?? 22
=
?? 11
=
?? 42
 d. 
?? 21
=
?? 11
=
?? 22
 
 
Answer: ( ?? ) 
Solution: 
We know that, ?? 
?? ?? is maximum when ?? = {
?? 2
,          ?? is even
?? +1
2
 or 
?? -1
2
,?? is odd
  
Therefore, max( ?? 
19
?? )= ?? 
19
9
= ?? 
max( ?? 
20
?? )= ?? 
20
10
= ?? 
max( ?? 
21
?? )= ?? 
21
11
= ?? 
 ?
?? ?? 
19
9
=
?? 20
10
× ?? 
19
9
=
?? 21
11
×
20
10
× ?? 
19
9
 
 
?? 1
=
?? 2
=
?? 42
11
 
 ?
?? 11
=
?? 22
=
?? 42
. 
 
2. Let ?? ( ?? )=
1
3
,?? ( ?? )=
1
6
 where ?? and ?? are independent events, then 
a. ?? (
?? ?? )=
2
3
 b. ?? (
?? ?? '
)=
5
6
 
c. ?? (
?? ?? '
)=
1
3
 d. ?? (
?? ?? )=
1
6
 Answer: ( ?? ) 
Solution: 
If ?? and ?? are independent events, then 
?? (
?? ?? )=
?? ( ?? n ?? )
?? ( ?? )
=
?? ( ?? ) ?? ( ?? )
?? ( ?? )
= ?? ( ?? ) 
Page 2


                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 1  
Date: 8
th
 January 2020 (Shift 1) 
Time: 9:30 A.M. to 12:30 P.M. 
Subject: Mathematics 
 
 
1. The maximum values of ?? 
19
?? , ?? 
20
?? , ?? 
21
?? are ?? ,?? ,?? respectively. Then, the relation 
between ?? ,?? ,?? is 
a. 
?? 22
=
?? 42
=
?? 11
 b. 
?? 11
=
?? 22
=
?? 42
 
c. 
?? 22
=
?? 11
=
?? 42
 d. 
?? 21
=
?? 11
=
?? 22
 
 
Answer: ( ?? ) 
Solution: 
We know that, ?? 
?? ?? is maximum when ?? = {
?? 2
,          ?? is even
?? +1
2
 or 
?? -1
2
,?? is odd
  
Therefore, max( ?? 
19
?? )= ?? 
19
9
= ?? 
max( ?? 
20
?? )= ?? 
20
10
= ?? 
max( ?? 
21
?? )= ?? 
21
11
= ?? 
 ?
?? ?? 
19
9
=
?? 20
10
× ?? 
19
9
=
?? 21
11
×
20
10
× ?? 
19
9
 
 
?? 1
=
?? 2
=
?? 42
11
 
 ?
?? 11
=
?? 22
=
?? 42
. 
 
2. Let ?? ( ?? )=
1
3
,?? ( ?? )=
1
6
 where ?? and ?? are independent events, then 
a. ?? (
?? ?? )=
2
3
 b. ?? (
?? ?? '
)=
5
6
 
c. ?? (
?? ?? '
)=
1
3
 d. ?? (
?? ?? )=
1
6
 Answer: ( ?? ) 
Solution: 
If ?? and ?? are independent events, then 
?? (
?? ?? )=
?? ( ?? n ?? )
?? ( ?? )
=
?? ( ?? ) ?? ( ?? )
?? ( ?? )
= ?? ( ?? ) 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 2  
 Therefore, ?? (
?? ?? )= ?? ( ?? )=
1
3
 ? ?? (
?? ?? '
)= ?? ( ?? )=
1
3
. 
 
3. If ?? ( ?? ) = 
8
2?? -8
-2?? 8
2?? +8
-2?? , then inverse of  ?? ( ?? ) is 
a. 
1
2
log
8
(
1+?? 1-?? ) 
b. 
1
2
log
8
(
1-?? 1+?? ) 
c. 
1
4
log
8
(
1-?? 1+?? ) d. 
1
4
log
8
(
1+?? 1-?? ) 
Answer: ( ?? ) 
Solution: 
?? ( ?? )=
8
2?? - 8
-2?? 8
2?? + 8
-2?? =
8
4?? - 1
8
4?? + 1
 
 Put ?? = 
8
4?? -1
8
4?? +1
 
Applying componendo-dividendo on both sides 
?? + 1
?? - 1
=
2× 8
4?? -2
 
 
?? +1
?? -1
= -8
4?? ? 8
4?? =
1+?? 1-?? 
 ? ?? =
1
4
log
8
(
1+?? 1-?? ) 
 ?? -1
( ?? )=
1
4
log
8
(
1+?? 1-?? ) . 
 
4. Roots of the equation ?? 2
+ ???? + 45 = 0,?? ? ?? lies on the curve |?? + 1| = 2v10, where ?? 
is a complex number, then 
a. ?? 2
+ ?? = 12  b. ?? 2
- ?? = 36 
c. ?? 2
- ?? = 30  d. ?? 2
+ ?? = 30 
Answer: ( ?? ) 
Solution: 
Given ?? 2
+ ???? + 45 = 0,?? ? ?? , let roots of the equation be ?? ± ???? 
Then, sum of roots = 2?? = -?? 
Product of roots = ?? 2
+ ?? 2
= 45 
As ?? ± ???? lies on |?? + 1| = 2v10, we get 
( ?? + 1)
2
+ ?? 2
= 40 
? ?? 2
+ ?? 2
+ 2?? + 1 = 40 
Page 3


                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 1  
Date: 8
th
 January 2020 (Shift 1) 
Time: 9:30 A.M. to 12:30 P.M. 
Subject: Mathematics 
 
 
1. The maximum values of ?? 
19
?? , ?? 
20
?? , ?? 
21
?? are ?? ,?? ,?? respectively. Then, the relation 
between ?? ,?? ,?? is 
a. 
?? 22
=
?? 42
=
?? 11
 b. 
?? 11
=
?? 22
=
?? 42
 
c. 
?? 22
=
?? 11
=
?? 42
 d. 
?? 21
=
?? 11
=
?? 22
 
 
Answer: ( ?? ) 
Solution: 
We know that, ?? 
?? ?? is maximum when ?? = {
?? 2
,          ?? is even
?? +1
2
 or 
?? -1
2
,?? is odd
  
Therefore, max( ?? 
19
?? )= ?? 
19
9
= ?? 
max( ?? 
20
?? )= ?? 
20
10
= ?? 
max( ?? 
21
?? )= ?? 
21
11
= ?? 
 ?
?? ?? 
19
9
=
?? 20
10
× ?? 
19
9
=
?? 21
11
×
20
10
× ?? 
19
9
 
 
?? 1
=
?? 2
=
?? 42
11
 
 ?
?? 11
=
?? 22
=
?? 42
. 
 
2. Let ?? ( ?? )=
1
3
,?? ( ?? )=
1
6
 where ?? and ?? are independent events, then 
a. ?? (
?? ?? )=
2
3
 b. ?? (
?? ?? '
)=
5
6
 
c. ?? (
?? ?? '
)=
1
3
 d. ?? (
?? ?? )=
1
6
 Answer: ( ?? ) 
Solution: 
If ?? and ?? are independent events, then 
?? (
?? ?? )=
?? ( ?? n ?? )
?? ( ?? )
=
?? ( ?? ) ?? ( ?? )
?? ( ?? )
= ?? ( ?? ) 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 2  
 Therefore, ?? (
?? ?? )= ?? ( ?? )=
1
3
 ? ?? (
?? ?? '
)= ?? ( ?? )=
1
3
. 
 
3. If ?? ( ?? ) = 
8
2?? -8
-2?? 8
2?? +8
-2?? , then inverse of  ?? ( ?? ) is 
a. 
1
2
log
8
(
1+?? 1-?? ) 
b. 
1
2
log
8
(
1-?? 1+?? ) 
c. 
1
4
log
8
(
1-?? 1+?? ) d. 
1
4
log
8
(
1+?? 1-?? ) 
Answer: ( ?? ) 
Solution: 
?? ( ?? )=
8
2?? - 8
-2?? 8
2?? + 8
-2?? =
8
4?? - 1
8
4?? + 1
 
 Put ?? = 
8
4?? -1
8
4?? +1
 
Applying componendo-dividendo on both sides 
?? + 1
?? - 1
=
2× 8
4?? -2
 
 
?? +1
?? -1
= -8
4?? ? 8
4?? =
1+?? 1-?? 
 ? ?? =
1
4
log
8
(
1+?? 1-?? ) 
 ?? -1
( ?? )=
1
4
log
8
(
1+?? 1-?? ) . 
 
4. Roots of the equation ?? 2
+ ???? + 45 = 0,?? ? ?? lies on the curve |?? + 1| = 2v10, where ?? 
is a complex number, then 
a. ?? 2
+ ?? = 12  b. ?? 2
- ?? = 36 
c. ?? 2
- ?? = 30  d. ?? 2
+ ?? = 30 
Answer: ( ?? ) 
Solution: 
Given ?? 2
+ ???? + 45 = 0,?? ? ?? , let roots of the equation be ?? ± ???? 
Then, sum of roots = 2?? = -?? 
Product of roots = ?? 2
+ ?? 2
= 45 
As ?? ± ???? lies on |?? + 1| = 2v10, we get 
( ?? + 1)
2
+ ?? 2
= 40 
? ?? 2
+ ?? 2
+ 2?? + 1 = 40 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 3  
? 45- ?? + 1 = 40 
? ?? = 6       
 ? ?? 2
- ?? = 30. 
 
5. Rolle’s theorem is applicable on ?? ( ?? )= ln(
?? 2
+?? 7?? ) in [3,4]. The value of ?? '' ( ?? ) is equal 
to 
a. 
1
12
 b. 
-1
12
 
c. 
-1
6
 d. 
1
6
 
Answer: ( ?? ) 
Solution: 
Rolle’s theorem is applicable on ?? ( ?? ) in [3,4] 
? ?? ( 3)= ?? ( 4) 
? ln(
9 + ?? 21
)= ln(
16+ ?? 28
) 
?
9+ ?? 21
=
16+ ?? 28
 
? 36+ 4?? = 48+ 3?? 
? ?? = 12 
Now,  
?? ( ?? )= ln(
?? 2
+ 12
7?? )? ?? '
( ?? )=
7?? ?? 2
+ 12
×
7?? × 2?? - ( ?? 2
+ 12)× 7
( 7?? )
2
 
?? '
( ?? )=
?? 2
- 12
?? ( ?? 2
+ 12)
 
?? '
( ?? )= 0 ? ?? = 2v3 
?? ''
( ?? )=
-?? 4
+ 48?? 2
+ 144
?? 2
( ?? 2
+ 12)
2
 
?? ''
( ?? )=
1
12
. 
 
6. Let ?? ( ?? )= ?? cos
-1
( sin ( -|?? |) ),?? ? ( -
?? 2
,
?? 2
) , then  
a. ?? '
( 0)= -
?? 2
 
b. ?? '
( ?? ) is not defined at ?? = 0 
c. ?? '
( ?? ) is decreasing in ( -
?? 2
, 0) and ?? '
( ?? ) is decreasing in ( 0,
?? 2
) 
d. ?? '
( ?? ) is increasing in ( -
?? 2
, 0) and ?? '( ?? ) is increasing in ( 0,
?? 2
) 
Page 4


                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 1  
Date: 8
th
 January 2020 (Shift 1) 
Time: 9:30 A.M. to 12:30 P.M. 
Subject: Mathematics 
 
 
1. The maximum values of ?? 
19
?? , ?? 
20
?? , ?? 
21
?? are ?? ,?? ,?? respectively. Then, the relation 
between ?? ,?? ,?? is 
a. 
?? 22
=
?? 42
=
?? 11
 b. 
?? 11
=
?? 22
=
?? 42
 
c. 
?? 22
=
?? 11
=
?? 42
 d. 
?? 21
=
?? 11
=
?? 22
 
 
Answer: ( ?? ) 
Solution: 
We know that, ?? 
?? ?? is maximum when ?? = {
?? 2
,          ?? is even
?? +1
2
 or 
?? -1
2
,?? is odd
  
Therefore, max( ?? 
19
?? )= ?? 
19
9
= ?? 
max( ?? 
20
?? )= ?? 
20
10
= ?? 
max( ?? 
21
?? )= ?? 
21
11
= ?? 
 ?
?? ?? 
19
9
=
?? 20
10
× ?? 
19
9
=
?? 21
11
×
20
10
× ?? 
19
9
 
 
?? 1
=
?? 2
=
?? 42
11
 
 ?
?? 11
=
?? 22
=
?? 42
. 
 
2. Let ?? ( ?? )=
1
3
,?? ( ?? )=
1
6
 where ?? and ?? are independent events, then 
a. ?? (
?? ?? )=
2
3
 b. ?? (
?? ?? '
)=
5
6
 
c. ?? (
?? ?? '
)=
1
3
 d. ?? (
?? ?? )=
1
6
 Answer: ( ?? ) 
Solution: 
If ?? and ?? are independent events, then 
?? (
?? ?? )=
?? ( ?? n ?? )
?? ( ?? )
=
?? ( ?? ) ?? ( ?? )
?? ( ?? )
= ?? ( ?? ) 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 2  
 Therefore, ?? (
?? ?? )= ?? ( ?? )=
1
3
 ? ?? (
?? ?? '
)= ?? ( ?? )=
1
3
. 
 
3. If ?? ( ?? ) = 
8
2?? -8
-2?? 8
2?? +8
-2?? , then inverse of  ?? ( ?? ) is 
a. 
1
2
log
8
(
1+?? 1-?? ) 
b. 
1
2
log
8
(
1-?? 1+?? ) 
c. 
1
4
log
8
(
1-?? 1+?? ) d. 
1
4
log
8
(
1+?? 1-?? ) 
Answer: ( ?? ) 
Solution: 
?? ( ?? )=
8
2?? - 8
-2?? 8
2?? + 8
-2?? =
8
4?? - 1
8
4?? + 1
 
 Put ?? = 
8
4?? -1
8
4?? +1
 
Applying componendo-dividendo on both sides 
?? + 1
?? - 1
=
2× 8
4?? -2
 
 
?? +1
?? -1
= -8
4?? ? 8
4?? =
1+?? 1-?? 
 ? ?? =
1
4
log
8
(
1+?? 1-?? ) 
 ?? -1
( ?? )=
1
4
log
8
(
1+?? 1-?? ) . 
 
4. Roots of the equation ?? 2
+ ???? + 45 = 0,?? ? ?? lies on the curve |?? + 1| = 2v10, where ?? 
is a complex number, then 
a. ?? 2
+ ?? = 12  b. ?? 2
- ?? = 36 
c. ?? 2
- ?? = 30  d. ?? 2
+ ?? = 30 
Answer: ( ?? ) 
Solution: 
Given ?? 2
+ ???? + 45 = 0,?? ? ?? , let roots of the equation be ?? ± ???? 
Then, sum of roots = 2?? = -?? 
Product of roots = ?? 2
+ ?? 2
= 45 
As ?? ± ???? lies on |?? + 1| = 2v10, we get 
( ?? + 1)
2
+ ?? 2
= 40 
? ?? 2
+ ?? 2
+ 2?? + 1 = 40 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 3  
? 45- ?? + 1 = 40 
? ?? = 6       
 ? ?? 2
- ?? = 30. 
 
5. Rolle’s theorem is applicable on ?? ( ?? )= ln(
?? 2
+?? 7?? ) in [3,4]. The value of ?? '' ( ?? ) is equal 
to 
a. 
1
12
 b. 
-1
12
 
c. 
-1
6
 d. 
1
6
 
Answer: ( ?? ) 
Solution: 
Rolle’s theorem is applicable on ?? ( ?? ) in [3,4] 
? ?? ( 3)= ?? ( 4) 
? ln(
9 + ?? 21
)= ln(
16+ ?? 28
) 
?
9+ ?? 21
=
16+ ?? 28
 
? 36+ 4?? = 48+ 3?? 
? ?? = 12 
Now,  
?? ( ?? )= ln(
?? 2
+ 12
7?? )? ?? '
( ?? )=
7?? ?? 2
+ 12
×
7?? × 2?? - ( ?? 2
+ 12)× 7
( 7?? )
2
 
?? '
( ?? )=
?? 2
- 12
?? ( ?? 2
+ 12)
 
?? '
( ?? )= 0 ? ?? = 2v3 
?? ''
( ?? )=
-?? 4
+ 48?? 2
+ 144
?? 2
( ?? 2
+ 12)
2
 
?? ''
( ?? )=
1
12
. 
 
6. Let ?? ( ?? )= ?? cos
-1
( sin ( -|?? |) ),?? ? ( -
?? 2
,
?? 2
) , then  
a. ?? '
( 0)= -
?? 2
 
b. ?? '
( ?? ) is not defined at ?? = 0 
c. ?? '
( ?? ) is decreasing in ( -
?? 2
, 0) and ?? '
( ?? ) is decreasing in ( 0,
?? 2
) 
d. ?? '
( ?? ) is increasing in ( -
?? 2
, 0) and ?? '( ?? ) is increasing in ( 0,
?? 2
) 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 4  
Answer: ( ?? ) 
Solution: 
?? ( ?? )= ?? cos
-1
( sin ( -|?? |) ) 
? ?? ( ?? )= ?? cos
-1
( -sin|?? |) 
? ?? ( ?? )= ?? [?? - cos
-1
( sin|?? |) ] 
? ?? ( ?? )= ?? [?? - (
?? 2
- sin
-1
( sin|?? |) ) ] 
? ?? ( ?? )= ?? (
?? 2
+ |?? |) 
? ?? ( ?? )= {
?? (
?? 2
+ ?? ), ?? = 0
?? (
?? 2
- ?? ), ?? < 0
 
? ?? '( ?? )= {
(
?? 2
+ 2?? ), ?? = 0
(
?? 2
- 2?? ), ?? < 0
 
Therefore, ?? '( ?? ) is decreasing ( -
?? 2
,0) and increasing in ( 0,
?? 2
) . 
 
7. Ellipse 2?? 2
+ ?? 2
= 1 and ?? = ???? meet at a point ?? in the first quadrant. Normal to the 
ellipse at ?? meets ?? -axis at ( -
1
3v2
,0) and ?? -axis at ( 0,?? ) , then |?? | is  
a. 
2
3
 
b. 
2v2
3
 
c. 
v2
3
 
d. 
2
v3
Answer: ( ?? ) 
Solution: 
 
Page 5


                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 1  
Date: 8
th
 January 2020 (Shift 1) 
Time: 9:30 A.M. to 12:30 P.M. 
Subject: Mathematics 
 
 
1. The maximum values of ?? 
19
?? , ?? 
20
?? , ?? 
21
?? are ?? ,?? ,?? respectively. Then, the relation 
between ?? ,?? ,?? is 
a. 
?? 22
=
?? 42
=
?? 11
 b. 
?? 11
=
?? 22
=
?? 42
 
c. 
?? 22
=
?? 11
=
?? 42
 d. 
?? 21
=
?? 11
=
?? 22
 
 
Answer: ( ?? ) 
Solution: 
We know that, ?? 
?? ?? is maximum when ?? = {
?? 2
,          ?? is even
?? +1
2
 or 
?? -1
2
,?? is odd
  
Therefore, max( ?? 
19
?? )= ?? 
19
9
= ?? 
max( ?? 
20
?? )= ?? 
20
10
= ?? 
max( ?? 
21
?? )= ?? 
21
11
= ?? 
 ?
?? ?? 
19
9
=
?? 20
10
× ?? 
19
9
=
?? 21
11
×
20
10
× ?? 
19
9
 
 
?? 1
=
?? 2
=
?? 42
11
 
 ?
?? 11
=
?? 22
=
?? 42
. 
 
2. Let ?? ( ?? )=
1
3
,?? ( ?? )=
1
6
 where ?? and ?? are independent events, then 
a. ?? (
?? ?? )=
2
3
 b. ?? (
?? ?? '
)=
5
6
 
c. ?? (
?? ?? '
)=
1
3
 d. ?? (
?? ?? )=
1
6
 Answer: ( ?? ) 
Solution: 
If ?? and ?? are independent events, then 
?? (
?? ?? )=
?? ( ?? n ?? )
?? ( ?? )
=
?? ( ?? ) ?? ( ?? )
?? ( ?? )
= ?? ( ?? ) 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 2  
 Therefore, ?? (
?? ?? )= ?? ( ?? )=
1
3
 ? ?? (
?? ?? '
)= ?? ( ?? )=
1
3
. 
 
3. If ?? ( ?? ) = 
8
2?? -8
-2?? 8
2?? +8
-2?? , then inverse of  ?? ( ?? ) is 
a. 
1
2
log
8
(
1+?? 1-?? ) 
b. 
1
2
log
8
(
1-?? 1+?? ) 
c. 
1
4
log
8
(
1-?? 1+?? ) d. 
1
4
log
8
(
1+?? 1-?? ) 
Answer: ( ?? ) 
Solution: 
?? ( ?? )=
8
2?? - 8
-2?? 8
2?? + 8
-2?? =
8
4?? - 1
8
4?? + 1
 
 Put ?? = 
8
4?? -1
8
4?? +1
 
Applying componendo-dividendo on both sides 
?? + 1
?? - 1
=
2× 8
4?? -2
 
 
?? +1
?? -1
= -8
4?? ? 8
4?? =
1+?? 1-?? 
 ? ?? =
1
4
log
8
(
1+?? 1-?? ) 
 ?? -1
( ?? )=
1
4
log
8
(
1+?? 1-?? ) . 
 
4. Roots of the equation ?? 2
+ ???? + 45 = 0,?? ? ?? lies on the curve |?? + 1| = 2v10, where ?? 
is a complex number, then 
a. ?? 2
+ ?? = 12  b. ?? 2
- ?? = 36 
c. ?? 2
- ?? = 30  d. ?? 2
+ ?? = 30 
Answer: ( ?? ) 
Solution: 
Given ?? 2
+ ???? + 45 = 0,?? ? ?? , let roots of the equation be ?? ± ???? 
Then, sum of roots = 2?? = -?? 
Product of roots = ?? 2
+ ?? 2
= 45 
As ?? ± ???? lies on |?? + 1| = 2v10, we get 
( ?? + 1)
2
+ ?? 2
= 40 
? ?? 2
+ ?? 2
+ 2?? + 1 = 40 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 3  
? 45- ?? + 1 = 40 
? ?? = 6       
 ? ?? 2
- ?? = 30. 
 
5. Rolle’s theorem is applicable on ?? ( ?? )= ln(
?? 2
+?? 7?? ) in [3,4]. The value of ?? '' ( ?? ) is equal 
to 
a. 
1
12
 b. 
-1
12
 
c. 
-1
6
 d. 
1
6
 
Answer: ( ?? ) 
Solution: 
Rolle’s theorem is applicable on ?? ( ?? ) in [3,4] 
? ?? ( 3)= ?? ( 4) 
? ln(
9 + ?? 21
)= ln(
16+ ?? 28
) 
?
9+ ?? 21
=
16+ ?? 28
 
? 36+ 4?? = 48+ 3?? 
? ?? = 12 
Now,  
?? ( ?? )= ln(
?? 2
+ 12
7?? )? ?? '
( ?? )=
7?? ?? 2
+ 12
×
7?? × 2?? - ( ?? 2
+ 12)× 7
( 7?? )
2
 
?? '
( ?? )=
?? 2
- 12
?? ( ?? 2
+ 12)
 
?? '
( ?? )= 0 ? ?? = 2v3 
?? ''
( ?? )=
-?? 4
+ 48?? 2
+ 144
?? 2
( ?? 2
+ 12)
2
 
?? ''
( ?? )=
1
12
. 
 
6. Let ?? ( ?? )= ?? cos
-1
( sin ( -|?? |) ),?? ? ( -
?? 2
,
?? 2
) , then  
a. ?? '
( 0)= -
?? 2
 
b. ?? '
( ?? ) is not defined at ?? = 0 
c. ?? '
( ?? ) is decreasing in ( -
?? 2
, 0) and ?? '
( ?? ) is decreasing in ( 0,
?? 2
) 
d. ?? '
( ?? ) is increasing in ( -
?? 2
, 0) and ?? '( ?? ) is increasing in ( 0,
?? 2
) 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 4  
Answer: ( ?? ) 
Solution: 
?? ( ?? )= ?? cos
-1
( sin ( -|?? |) ) 
? ?? ( ?? )= ?? cos
-1
( -sin|?? |) 
? ?? ( ?? )= ?? [?? - cos
-1
( sin|?? |) ] 
? ?? ( ?? )= ?? [?? - (
?? 2
- sin
-1
( sin|?? |) ) ] 
? ?? ( ?? )= ?? (
?? 2
+ |?? |) 
? ?? ( ?? )= {
?? (
?? 2
+ ?? ), ?? = 0
?? (
?? 2
- ?? ), ?? < 0
 
? ?? '( ?? )= {
(
?? 2
+ 2?? ), ?? = 0
(
?? 2
- 2?? ), ?? < 0
 
Therefore, ?? '( ?? ) is decreasing ( -
?? 2
,0) and increasing in ( 0,
?? 2
) . 
 
7. Ellipse 2?? 2
+ ?? 2
= 1 and ?? = ???? meet at a point ?? in the first quadrant. Normal to the 
ellipse at ?? meets ?? -axis at ( -
1
3v2
,0) and ?? -axis at ( 0,?? ) , then |?? | is  
a. 
2
3
 
b. 
2v2
3
 
c. 
v2
3
 
d. 
2
v3
Answer: ( ?? ) 
Solution: 
 
                                               8
th
 January 2020 (Shift 1), Mathematics                                              Page | 5  
Let ?? = ( ?? 1
,?? 1
) 
2?? 2
+ ?? 2
= 1 is given equation of ellipse. 
? 4?? + 2?? ?? '
= 0 
? ?? '
|
( ?? 1
,?? 1
)
= -
2?? 1
?? 1
 
Therefore, slope of normal at ?? ( ?? 1
,?? 1
) is  
?? 1
2?? 1
 
Equation of normal at ?? ( ?? 1
,?? 1
) is  
( ?? - ?? 1
)=
?? 1
2?? 1
( ?? - ?? 1
) 
It passes through ( -
1
3v2
,0) 
? -?? 1
=
?? 1
2?? 1
( -
1
3v2
- ?? 1
) 
? ?? 1
=
1
3v2
 
? ?? 1
=
2v2
3
    as ?? lies in first quadrant 
Since ( 0, ?? ) lies on the normal of the ellipse at point ?? , hence we get 
?? =
?? 1
2
=
v2
3
 
 
8. If ?????? is a triangle whose vertices are ?? ( 1, -1) , ?? ( 0,2) , ?? ( ?? '
, ?? ') and area of ??????? is 
5,  and ?? ( ?? '
, ?? ') lies on 3?? + ?? - 4?? = 0, then
a. ?? = 3 b.    ?? = 4  
c. ?? = -3 d. ?? = 2  
Answer: ( ?? ) 
Solution:  
Area of triangle is  
?? =
1
2
|
0 2 1
1 -1 1
?? '
?? '
1
| = ±5 
-2( 1- ?? '
)+ ( ?? '
+ ?? '
)= ±10 
-2+ 2?? '
+ ?? '
+ ?? '
= ±10 
3?? '
+ ?? '
= 12 or 3?? '
+ ?? '
= -8 
? ?? = 3 or -2 
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