Page 1
JEE Main Previous Year Questions
(2025): Binomial Theorem & its
Applications
Q1: If ? ?
?? ?? =??
????
?? ?? ?? +?? ?? ?? +?? =
?? ?? , ?????? ( ?? , ?? )= ?? , then ?? - ?? is equal to ____ .
JEE Main 2025 (Online) 22nd January Morning Shift
Ans: 2035
Solution:
( 1 + ?? )
11
=
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
?
0
1
?( 1 + ?? )
11
???? = ?
0
1
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 - ?? )
12
12
]
0
1
=
11
?? 0?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
+ ? +
11
?? 11
?? 12
12
]
0
1
2
12
- 1
12
= ?? 0
+
?? 1
2
+
?? 2
3
+ ? +
?? 11
12
? ( 1)
Now,
?
-1
0
?( 1 + ?? )
11
???? = ?
-1
0
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 + ?? )
12
12
]
-1
0
=
11
?? 0
?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
3
+ ? +
11
?? 11
?? 12
12
]
-1
0
( 2)
1
12
= ?? 0
-
?? 1
2
+
?? 2
3
.
(1) -( 2)
=
2
12
- 2
12
= 2 [
?? 1
2
+
?? 3
4
+ ? ]
? ?
?? =0
5
?
?? 2?? +1
2?? + 2
=
2
11
- 1
12
=
2047
12
=
?? ??
= 2047- 12 = 2035
Q2: If ?
?? =?? ????
?
?? ?? (
????
?? ?? )
??
????
?? ?? -?? = ?? × ?? ????
, then ?? is equal to ____ .
Ans: 465
Solution:
Page 2
JEE Main Previous Year Questions
(2025): Binomial Theorem & its
Applications
Q1: If ? ?
?? ?? =??
????
?? ?? ?? +?? ?? ?? +?? =
?? ?? , ?????? ( ?? , ?? )= ?? , then ?? - ?? is equal to ____ .
JEE Main 2025 (Online) 22nd January Morning Shift
Ans: 2035
Solution:
( 1 + ?? )
11
=
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
?
0
1
?( 1 + ?? )
11
???? = ?
0
1
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 - ?? )
12
12
]
0
1
=
11
?? 0?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
+ ? +
11
?? 11
?? 12
12
]
0
1
2
12
- 1
12
= ?? 0
+
?? 1
2
+
?? 2
3
+ ? +
?? 11
12
? ( 1)
Now,
?
-1
0
?( 1 + ?? )
11
???? = ?
-1
0
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 + ?? )
12
12
]
-1
0
=
11
?? 0
?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
3
+ ? +
11
?? 11
?? 12
12
]
-1
0
( 2)
1
12
= ?? 0
-
?? 1
2
+
?? 2
3
.
(1) -( 2)
=
2
12
- 2
12
= 2 [
?? 1
2
+
?? 3
4
+ ? ]
? ?
?? =0
5
?
?? 2?? +1
2?? + 2
=
2
11
- 1
12
=
2047
12
=
?? ??
= 2047- 12 = 2035
Q2: If ?
?? =?? ????
?
?? ?? (
????
?? ?? )
??
????
?? ?? -?? = ?? × ?? ????
, then ?? is equal to ____ .
Ans: 465
Solution:
?
r=1
30
?
r
2
(
30
C
r
)
2
30
C
r-1
= ?
r=1
30
?r
2
(
31 - r
r
)·
30!
r! ( 30 - r) !
(?
30
C
r
30
C
r-1
=
30 - r + 1
r
=
31 - r
r
)
= ?
r=1
30
?
( 31 - r) 30!
( r - 1) ! ( 30 - r) !
= 30?
r=1
30
?
( 31 - r) 29!
( r - 1) ! ( 30 - r) !
= 30?
r=1
30
?( 30 - r + 1)
29
C
30-r
= 30( ?
r=1
30
?( 31 - r)
29
C
30-r
+ ?
r=1
30
?
29
C
30-r
)
= 30( 29 × 2
28
+ 2
29
)= 30( 29 + 2) 2
28
= 15 × 31 × 2
29
= 465 ( 2
29
)
?? = 465
Q3: The sum of all rational terms in the expansion of ( ?? + ?? ?? /?? + ?? ?? /?? )
?? is equal to ____ .
JEE Main 2025 (Online) 23rd January Morning Shift
Ans: 612
Solution:
( 1 + 2
1
3
+ 3
1
2
)
6
=
6
?? 1
?? 2
?? 3
( 1)
?? 1
( 2)
?? 2
3
( 3)
?? 3
2
?? ?? ?? ?? ?? ??
6 0 0
4 0 2
2 0 4
0 0 6
3 3 0
1 3 2
0 6 0
=
60
600
+
6
402
( 3)+
6
20 | 4
( 3)
2
+
6
0 | 0 | 6
( 3)
3
+
6
|3|3 | 0
( 2)+
6
1|3|2
( 2)
1
( 3)
1
+
6
0|6|0
( 2)
2
= 1 + 45 + 135+ 27 + 40 + 360+ 4 = 612
Page 3
JEE Main Previous Year Questions
(2025): Binomial Theorem & its
Applications
Q1: If ? ?
?? ?? =??
????
?? ?? ?? +?? ?? ?? +?? =
?? ?? , ?????? ( ?? , ?? )= ?? , then ?? - ?? is equal to ____ .
JEE Main 2025 (Online) 22nd January Morning Shift
Ans: 2035
Solution:
( 1 + ?? )
11
=
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
?
0
1
?( 1 + ?? )
11
???? = ?
0
1
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 - ?? )
12
12
]
0
1
=
11
?? 0?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
+ ? +
11
?? 11
?? 12
12
]
0
1
2
12
- 1
12
= ?? 0
+
?? 1
2
+
?? 2
3
+ ? +
?? 11
12
? ( 1)
Now,
?
-1
0
?( 1 + ?? )
11
???? = ?
-1
0
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 + ?? )
12
12
]
-1
0
=
11
?? 0
?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
3
+ ? +
11
?? 11
?? 12
12
]
-1
0
( 2)
1
12
= ?? 0
-
?? 1
2
+
?? 2
3
.
(1) -( 2)
=
2
12
- 2
12
= 2 [
?? 1
2
+
?? 3
4
+ ? ]
? ?
?? =0
5
?
?? 2?? +1
2?? + 2
=
2
11
- 1
12
=
2047
12
=
?? ??
= 2047- 12 = 2035
Q2: If ?
?? =?? ????
?
?? ?? (
????
?? ?? )
??
????
?? ?? -?? = ?? × ?? ????
, then ?? is equal to ____ .
Ans: 465
Solution:
?
r=1
30
?
r
2
(
30
C
r
)
2
30
C
r-1
= ?
r=1
30
?r
2
(
31 - r
r
)·
30!
r! ( 30 - r) !
(?
30
C
r
30
C
r-1
=
30 - r + 1
r
=
31 - r
r
)
= ?
r=1
30
?
( 31 - r) 30!
( r - 1) ! ( 30 - r) !
= 30?
r=1
30
?
( 31 - r) 29!
( r - 1) ! ( 30 - r) !
= 30?
r=1
30
?( 30 - r + 1)
29
C
30-r
= 30( ?
r=1
30
?( 31 - r)
29
C
30-r
+ ?
r=1
30
?
29
C
30-r
)
= 30( 29 × 2
28
+ 2
29
)= 30( 29 + 2) 2
28
= 15 × 31 × 2
29
= 465 ( 2
29
)
?? = 465
Q3: The sum of all rational terms in the expansion of ( ?? + ?? ?? /?? + ?? ?? /?? )
?? is equal to ____ .
JEE Main 2025 (Online) 23rd January Morning Shift
Ans: 612
Solution:
( 1 + 2
1
3
+ 3
1
2
)
6
=
6
?? 1
?? 2
?? 3
( 1)
?? 1
( 2)
?? 2
3
( 3)
?? 3
2
?? ?? ?? ?? ?? ??
6 0 0
4 0 2
2 0 4
0 0 6
3 3 0
1 3 2
0 6 0
=
60
600
+
6
402
( 3)+
6
20 | 4
( 3)
2
+
6
0 | 0 | 6
( 3)
3
+
6
|3|3 | 0
( 2)+
6
1|3|2
( 2)
1
( 3)
1
+
6
0|6|0
( 2)
2
= 1 + 45 + 135+ 27 + 40 + 360+ 4 = 612
Q4: If ?? = ?? + ?
?? =?? ?? ?( -?? )
?? -??
????
?? ?? ?? -?? , then the distance of the point ( ???? , v?? ) from the
line ???? - v?? ?? + ?? = ?? is ____ .
JEE Main 2025 (Online) 28th January Morning Shift
Ans: 5
Solution:
?? = 1 + ?
r=1
6
?( -1)
r-112
C
2r-1
3
r-1
?? = 1 + ?
r=1
6
?
12
C
2r-1
( v 3i)
2t-1
v 3i
i = iota, let v3i = x
?? = 1 +
1
v3i
(
12
C
1
x +
12
C
3
x
3
+ ? .
12
C
11
x
11
)
= 1 +
1
v3i
(
( 1 + v3i)
12
- ( 1 - v3i)
12
2
)
= 1 +
1
v3i
(
( -2?? 2
)
12
- ( 2?? )
12
2
) = 1
so distance of ( 12, v3) from ?? - v3?? + 1 = 0 is
12 - 3 + 1
2
= 5
Q5: Let ( ?? + ?? + ?? ?? )
????
= ?? ?? + ?? ?? ?? + ?? ?? ?? ?? + ? + ?? ????
?? ????
. If ( ?? ?? + ?? ?? + ?? ?? + ? +
?? ????
)- ???? ?? ?? = ?????? ?? , then ?? is equal to ____ .
Ans: 239
Solution:
Let ?? ( ?? )= ( 1 + ?? + ?? 2
)
10
= ?
?? =0
20
??? ?? ?? ??
The sum of odd coefficients: ?? odd
= ?? 1
+ ?? 3
+ ?? 5
+ ? + ?? 19
Subtracting 11?? 2
from above will give the answer
?? odd
=
?? ( 1)- ?? ( -1)
2
?? ( 1)= ( 1 + 1 + 1)
10
= 3
10
?? ( -1)= ( 1 - 1 + 1)
10
= ( 1)
10
= 1
?? odd
= ?
odd
??? ?? =
3
10
- 1
2
Now for ?? 2
1 + ?? + ?? 2
=
1 - ?? 3
1 - ?? ? ?? ( ?? )= (
1 - ?? 3
1 - ?? ) =
( 1 - ?? 3
)
10
( 1 - ?? )
10
Now use:
( 1 - ?? 3
)
10
= ?
?? =0
10
?( -1)
?? (
10
?? )?? 3??
( 1 - ?? )
-10
= ?
?? =0
8
?(
?? + 9
9
)?? ??
So
Page 4
JEE Main Previous Year Questions
(2025): Binomial Theorem & its
Applications
Q1: If ? ?
?? ?? =??
????
?? ?? ?? +?? ?? ?? +?? =
?? ?? , ?????? ( ?? , ?? )= ?? , then ?? - ?? is equal to ____ .
JEE Main 2025 (Online) 22nd January Morning Shift
Ans: 2035
Solution:
( 1 + ?? )
11
=
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
?
0
1
?( 1 + ?? )
11
???? = ?
0
1
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 - ?? )
12
12
]
0
1
=
11
?? 0?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
+ ? +
11
?? 11
?? 12
12
]
0
1
2
12
- 1
12
= ?? 0
+
?? 1
2
+
?? 2
3
+ ? +
?? 11
12
? ( 1)
Now,
?
-1
0
?( 1 + ?? )
11
???? = ?
-1
0
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 + ?? )
12
12
]
-1
0
=
11
?? 0
?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
3
+ ? +
11
?? 11
?? 12
12
]
-1
0
( 2)
1
12
= ?? 0
-
?? 1
2
+
?? 2
3
.
(1) -( 2)
=
2
12
- 2
12
= 2 [
?? 1
2
+
?? 3
4
+ ? ]
? ?
?? =0
5
?
?? 2?? +1
2?? + 2
=
2
11
- 1
12
=
2047
12
=
?? ??
= 2047- 12 = 2035
Q2: If ?
?? =?? ????
?
?? ?? (
????
?? ?? )
??
????
?? ?? -?? = ?? × ?? ????
, then ?? is equal to ____ .
Ans: 465
Solution:
?
r=1
30
?
r
2
(
30
C
r
)
2
30
C
r-1
= ?
r=1
30
?r
2
(
31 - r
r
)·
30!
r! ( 30 - r) !
(?
30
C
r
30
C
r-1
=
30 - r + 1
r
=
31 - r
r
)
= ?
r=1
30
?
( 31 - r) 30!
( r - 1) ! ( 30 - r) !
= 30?
r=1
30
?
( 31 - r) 29!
( r - 1) ! ( 30 - r) !
= 30?
r=1
30
?( 30 - r + 1)
29
C
30-r
= 30( ?
r=1
30
?( 31 - r)
29
C
30-r
+ ?
r=1
30
?
29
C
30-r
)
= 30( 29 × 2
28
+ 2
29
)= 30( 29 + 2) 2
28
= 15 × 31 × 2
29
= 465 ( 2
29
)
?? = 465
Q3: The sum of all rational terms in the expansion of ( ?? + ?? ?? /?? + ?? ?? /?? )
?? is equal to ____ .
JEE Main 2025 (Online) 23rd January Morning Shift
Ans: 612
Solution:
( 1 + 2
1
3
+ 3
1
2
)
6
=
6
?? 1
?? 2
?? 3
( 1)
?? 1
( 2)
?? 2
3
( 3)
?? 3
2
?? ?? ?? ?? ?? ??
6 0 0
4 0 2
2 0 4
0 0 6
3 3 0
1 3 2
0 6 0
=
60
600
+
6
402
( 3)+
6
20 | 4
( 3)
2
+
6
0 | 0 | 6
( 3)
3
+
6
|3|3 | 0
( 2)+
6
1|3|2
( 2)
1
( 3)
1
+
6
0|6|0
( 2)
2
= 1 + 45 + 135+ 27 + 40 + 360+ 4 = 612
Q4: If ?? = ?? + ?
?? =?? ?? ?( -?? )
?? -??
????
?? ?? ?? -?? , then the distance of the point ( ???? , v?? ) from the
line ???? - v?? ?? + ?? = ?? is ____ .
JEE Main 2025 (Online) 28th January Morning Shift
Ans: 5
Solution:
?? = 1 + ?
r=1
6
?( -1)
r-112
C
2r-1
3
r-1
?? = 1 + ?
r=1
6
?
12
C
2r-1
( v 3i)
2t-1
v 3i
i = iota, let v3i = x
?? = 1 +
1
v3i
(
12
C
1
x +
12
C
3
x
3
+ ? .
12
C
11
x
11
)
= 1 +
1
v3i
(
( 1 + v3i)
12
- ( 1 - v3i)
12
2
)
= 1 +
1
v3i
(
( -2?? 2
)
12
- ( 2?? )
12
2
) = 1
so distance of ( 12, v3) from ?? - v3?? + 1 = 0 is
12 - 3 + 1
2
= 5
Q5: Let ( ?? + ?? + ?? ?? )
????
= ?? ?? + ?? ?? ?? + ?? ?? ?? ?? + ? + ?? ????
?? ????
. If ( ?? ?? + ?? ?? + ?? ?? + ? +
?? ????
)- ???? ?? ?? = ?????? ?? , then ?? is equal to ____ .
Ans: 239
Solution:
Let ?? ( ?? )= ( 1 + ?? + ?? 2
)
10
= ?
?? =0
20
??? ?? ?? ??
The sum of odd coefficients: ?? odd
= ?? 1
+ ?? 3
+ ?? 5
+ ? + ?? 19
Subtracting 11?? 2
from above will give the answer
?? odd
=
?? ( 1)- ?? ( -1)
2
?? ( 1)= ( 1 + 1 + 1)
10
= 3
10
?? ( -1)= ( 1 - 1 + 1)
10
= ( 1)
10
= 1
?? odd
= ?
odd
??? ?? =
3
10
- 1
2
Now for ?? 2
1 + ?? + ?? 2
=
1 - ?? 3
1 - ?? ? ?? ( ?? )= (
1 - ?? 3
1 - ?? ) =
( 1 - ?? 3
)
10
( 1 - ?? )
10
Now use:
( 1 - ?? 3
)
10
= ?
?? =0
10
?( -1)
?? (
10
?? )?? 3??
( 1 - ?? )
-10
= ?
?? =0
8
?(
?? + 9
9
)?? ??
So
?? ( ?? )= ( ?
?? =0
10
?( -1)
?? (
10
?? )?? 3?? )· ( ?
?? =0
8
?(
?? + 9
9
)?? ?? )
Only the term with ?? 0
from the first sum (i.e., ?? = 0 ) can contribute to ?? 2
, since all other ?? = 1
gives ?? 3?? = ?? 3
From ( 1 - ?? 3
)
10
: the ?? 0
term is (
10
0
)= 1
From ( 1 - ?? )
-10
: the coefficient of ?? 2
is
(
2 + 9
9
)= (
11
9
)= 55
Hence, ?? 2
= 1.55 = 55
Now, ?? odd
- 11?? 2
=
3
10
-1
2
- 11 · 55 = 121 ??
3
10
= 59049
So:
?? =
59049- 1
2
- 605 =
59048
2
- 605
= 29524- 605 = 28919
So:
121 ?? = 28919 ? ?? =
28919
121
= 239
Q6: The sum of the series
?? × ?? ×
????
?? ?? - ?? × ?? ×
????
?? ?? + ?? × ?? ×
????
?? ?? - ?? × ?? ×
????
?? ?? + ? ? + ???? × ???? ×
????
?? ????
, is equal to ____ .
JEE Main 2025 (Online) 7th April Evening Shift
Ans: 34
Solution:
( 1 - x)
20
=
20
C
0
-
20
C
1
x +
20
C
2
x
2
… … +
20
C
20
x
20
( 1 - x)
20
x
2
=
20
C
0
x
2
-
20
C
1
x
+
20
C
2
-
20
C
3
x +
20
C
4
x
2
…
Diff twice and put x = 1
= 6 -
20
C
1
( 2)+ A
A = 40 - 6 = 34
Q7: The product of the last two digits of (1919)
????????
is
JEE Main 2025 (Online) 8th April Evening Shift
Ans: 63
Solution:
( 1919)
1919
= ( 1920- 1)
1919
=
1919
C
0
( 1920 )
1919
-
1919
C
1
( 1920 )
1918
+ ?.
+
1919
C
1918
( 1920 )
1
-
1919
C
1919
= 100 ?? + 1919 × 1920- 1
Page 5
JEE Main Previous Year Questions
(2025): Binomial Theorem & its
Applications
Q1: If ? ?
?? ?? =??
????
?? ?? ?? +?? ?? ?? +?? =
?? ?? , ?????? ( ?? , ?? )= ?? , then ?? - ?? is equal to ____ .
JEE Main 2025 (Online) 22nd January Morning Shift
Ans: 2035
Solution:
( 1 + ?? )
11
=
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
?
0
1
?( 1 + ?? )
11
???? = ?
0
1
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 - ?? )
12
12
]
0
1
=
11
?? 0?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
+ ? +
11
?? 11
?? 12
12
]
0
1
2
12
- 1
12
= ?? 0
+
?? 1
2
+
?? 2
3
+ ? +
?? 11
12
? ( 1)
Now,
?
-1
0
?( 1 + ?? )
11
???? = ?
-1
0
?(
11
?? 0
+
11
?? 1
?? +
11
?? 2
?? 2
+ ? +
11
?? 11
?? 11
) ????
( 1 + ?? )
12
12
]
-1
0
=
11
?? 0
?? +
11
?? 1
?? 2
2
+
11
?? 2
?? 3
3
+ ? +
11
?? 11
?? 12
12
]
-1
0
( 2)
1
12
= ?? 0
-
?? 1
2
+
?? 2
3
.
(1) -( 2)
=
2
12
- 2
12
= 2 [
?? 1
2
+
?? 3
4
+ ? ]
? ?
?? =0
5
?
?? 2?? +1
2?? + 2
=
2
11
- 1
12
=
2047
12
=
?? ??
= 2047- 12 = 2035
Q2: If ?
?? =?? ????
?
?? ?? (
????
?? ?? )
??
????
?? ?? -?? = ?? × ?? ????
, then ?? is equal to ____ .
Ans: 465
Solution:
?
r=1
30
?
r
2
(
30
C
r
)
2
30
C
r-1
= ?
r=1
30
?r
2
(
31 - r
r
)·
30!
r! ( 30 - r) !
(?
30
C
r
30
C
r-1
=
30 - r + 1
r
=
31 - r
r
)
= ?
r=1
30
?
( 31 - r) 30!
( r - 1) ! ( 30 - r) !
= 30?
r=1
30
?
( 31 - r) 29!
( r - 1) ! ( 30 - r) !
= 30?
r=1
30
?( 30 - r + 1)
29
C
30-r
= 30( ?
r=1
30
?( 31 - r)
29
C
30-r
+ ?
r=1
30
?
29
C
30-r
)
= 30( 29 × 2
28
+ 2
29
)= 30( 29 + 2) 2
28
= 15 × 31 × 2
29
= 465 ( 2
29
)
?? = 465
Q3: The sum of all rational terms in the expansion of ( ?? + ?? ?? /?? + ?? ?? /?? )
?? is equal to ____ .
JEE Main 2025 (Online) 23rd January Morning Shift
Ans: 612
Solution:
( 1 + 2
1
3
+ 3
1
2
)
6
=
6
?? 1
?? 2
?? 3
( 1)
?? 1
( 2)
?? 2
3
( 3)
?? 3
2
?? ?? ?? ?? ?? ??
6 0 0
4 0 2
2 0 4
0 0 6
3 3 0
1 3 2
0 6 0
=
60
600
+
6
402
( 3)+
6
20 | 4
( 3)
2
+
6
0 | 0 | 6
( 3)
3
+
6
|3|3 | 0
( 2)+
6
1|3|2
( 2)
1
( 3)
1
+
6
0|6|0
( 2)
2
= 1 + 45 + 135+ 27 + 40 + 360+ 4 = 612
Q4: If ?? = ?? + ?
?? =?? ?? ?( -?? )
?? -??
????
?? ?? ?? -?? , then the distance of the point ( ???? , v?? ) from the
line ???? - v?? ?? + ?? = ?? is ____ .
JEE Main 2025 (Online) 28th January Morning Shift
Ans: 5
Solution:
?? = 1 + ?
r=1
6
?( -1)
r-112
C
2r-1
3
r-1
?? = 1 + ?
r=1
6
?
12
C
2r-1
( v 3i)
2t-1
v 3i
i = iota, let v3i = x
?? = 1 +
1
v3i
(
12
C
1
x +
12
C
3
x
3
+ ? .
12
C
11
x
11
)
= 1 +
1
v3i
(
( 1 + v3i)
12
- ( 1 - v3i)
12
2
)
= 1 +
1
v3i
(
( -2?? 2
)
12
- ( 2?? )
12
2
) = 1
so distance of ( 12, v3) from ?? - v3?? + 1 = 0 is
12 - 3 + 1
2
= 5
Q5: Let ( ?? + ?? + ?? ?? )
????
= ?? ?? + ?? ?? ?? + ?? ?? ?? ?? + ? + ?? ????
?? ????
. If ( ?? ?? + ?? ?? + ?? ?? + ? +
?? ????
)- ???? ?? ?? = ?????? ?? , then ?? is equal to ____ .
Ans: 239
Solution:
Let ?? ( ?? )= ( 1 + ?? + ?? 2
)
10
= ?
?? =0
20
??? ?? ?? ??
The sum of odd coefficients: ?? odd
= ?? 1
+ ?? 3
+ ?? 5
+ ? + ?? 19
Subtracting 11?? 2
from above will give the answer
?? odd
=
?? ( 1)- ?? ( -1)
2
?? ( 1)= ( 1 + 1 + 1)
10
= 3
10
?? ( -1)= ( 1 - 1 + 1)
10
= ( 1)
10
= 1
?? odd
= ?
odd
??? ?? =
3
10
- 1
2
Now for ?? 2
1 + ?? + ?? 2
=
1 - ?? 3
1 - ?? ? ?? ( ?? )= (
1 - ?? 3
1 - ?? ) =
( 1 - ?? 3
)
10
( 1 - ?? )
10
Now use:
( 1 - ?? 3
)
10
= ?
?? =0
10
?( -1)
?? (
10
?? )?? 3??
( 1 - ?? )
-10
= ?
?? =0
8
?(
?? + 9
9
)?? ??
So
?? ( ?? )= ( ?
?? =0
10
?( -1)
?? (
10
?? )?? 3?? )· ( ?
?? =0
8
?(
?? + 9
9
)?? ?? )
Only the term with ?? 0
from the first sum (i.e., ?? = 0 ) can contribute to ?? 2
, since all other ?? = 1
gives ?? 3?? = ?? 3
From ( 1 - ?? 3
)
10
: the ?? 0
term is (
10
0
)= 1
From ( 1 - ?? )
-10
: the coefficient of ?? 2
is
(
2 + 9
9
)= (
11
9
)= 55
Hence, ?? 2
= 1.55 = 55
Now, ?? odd
- 11?? 2
=
3
10
-1
2
- 11 · 55 = 121 ??
3
10
= 59049
So:
?? =
59049- 1
2
- 605 =
59048
2
- 605
= 29524- 605 = 28919
So:
121 ?? = 28919 ? ?? =
28919
121
= 239
Q6: The sum of the series
?? × ?? ×
????
?? ?? - ?? × ?? ×
????
?? ?? + ?? × ?? ×
????
?? ?? - ?? × ?? ×
????
?? ?? + ? ? + ???? × ???? ×
????
?? ????
, is equal to ____ .
JEE Main 2025 (Online) 7th April Evening Shift
Ans: 34
Solution:
( 1 - x)
20
=
20
C
0
-
20
C
1
x +
20
C
2
x
2
… … +
20
C
20
x
20
( 1 - x)
20
x
2
=
20
C
0
x
2
-
20
C
1
x
+
20
C
2
-
20
C
3
x +
20
C
4
x
2
…
Diff twice and put x = 1
= 6 -
20
C
1
( 2)+ A
A = 40 - 6 = 34
Q7: The product of the last two digits of (1919)
????????
is
JEE Main 2025 (Online) 8th April Evening Shift
Ans: 63
Solution:
( 1919)
1919
= ( 1920- 1)
1919
=
1919
C
0
( 1920 )
1919
-
1919
C
1
( 1920 )
1918
+ ?.
+
1919
C
1918
( 1920 )
1
-
1919
C
1919
= 100 ?? + 1919 × 1920- 1
= 100 ?? + 3684480- 1
= 100 ?? + ? … … . .79 (last two digit)
? Number having last two digit 79
? Product of last two digit 63
Q8: Let ?? , ?? , ?? and ?? be the coefficients of ?? ?? , ?? ?? , ?? ?? and ?? respectively in the expansion
of ( ?? + v?? ?? - ?? )
?? + ( ?? - v?? ?? - ?? )
?? , ?? > ?? . If ?? and ?? satisfy the equations ???? + ???? =
???? , ???? + ???? = ???? , then ?? + ?? equals :
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. 4
B. 3
C. 5
D. 8
Ans: C
Solution:
To find the sum of ?? and ?? , we first need to expand the expression:
( ?? +
v
?? 3
- 1)
5
+ ( ?? -
v
?? 3
- 1)
5
Using the Binomial Theorem, the expansion yields:
= 2(
5
?? 0
· ?? 5
+
5
?? 2
· ?? 3
( ?? 3
- 1)+
5
?? 4
· ?? ( ?? 3
- 1)
2
)
Simplifying this, we obtain:
= 2( 5?? 7
+ 10?? 6
+ ?? 5
- 10?? 4
- 10?? 3
+ 5?? )
From this expansion, we can identify the coefficients:
The coefficient of ?? 7
is ?? = 10
The coefficient of ?? 5
is ?? = 2
The coefficient of ?? 3
is ?? = -20
The coefficient of ?? is ?? = 10
Given the equations:
???? + ???? = 18
???? + ???? = 20
Substituting in the coefficients:
10?? + 2?? = 18
-20?? + 10?? = 20
By solving these equations, we find:
From 10?? + 2?? = 18, simplify to 5?? + ?? = 9.
From -20?? + 10?? = 20, simplify to -2?? + ?? = 2.
Solving these linear equations simultaneously, we find:
Subtracting equation 2 from equation 1 :
5?? + ?? = 9
-( -2?? + ?? = 2)
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