Page 1
JEE Main Previous Year Questions (2021-2026):
Binomial Theorem
(January 2026)
Q1: Given below are two statements :
Statement I : 25
13
+ 20
13
+ 8
13
+ 3
13
is divisible by 7.
Statement II : The integral part of (7 + 4v3)
25
is an odd number.
In the light of the above statements, choose the correct answer from the options given
below :
(a) Statement I is false but Statement II is true
(b) Both Statement I and Statement II are false
(c) Both Statement I and Statement II are true
(d) Statement I is true but Statement II is false
Ans: (c)
Sol:
Statement I: 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7.
Key concept : If n is odd, xn + yn = (x + y)(xn ?¹ - xn ?²y + xn ?³y² - · · · - xyn ?² + yn ?¹) So, xn + yn is
divisible by x + y.
In the given statement :
25¹³ + 3¹³ is divisible by 25 + 3 = 28.
25¹³ + 3¹³ is also divisible by 7 because 28 is divisible by 7.
So, 25¹³ + 3¹³ = 7 · I 1..........(1) ( I 1 is a positive integer).
Similarly :
20¹³ + 8¹³ is divisible by 20 + 8 = 28.
20¹³ + 8¹³ is divisible by 7.
So, 20¹³ + 8¹³ = 7 · I 2 ..........(2) ( I 2 is a positive integer).
Add (1) & (2) :
25¹³ + 3¹³ + 20¹³ + 8¹³ = 7(I 1 + I 2)
So, 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7. Statement I is true.
Statement II: The integral part of (7 + 4v3)² 5 is an odd number.
Let X = (7 + 4v3)² 5. Let I be the integral part and f be the fractional part ( $0
Adding the two expansions:
(7 + 4v3)² 5 + (7 - 4v3)² 5 = I + f + f'
Using the binomial expansion (a + b)n + (a - b)n = 2[an + (n 2)an ?²b² + . . .], we see that the sum is
always an even integer because of the factor of 2.
I + f + f' = Even Integer
Since I is an integer, f + f' must also be an integer. Given 0 < f < 1 and 0 < f' < 1, the only
possible integer value for their sum is f + f' = 1.
I + 1 = Even Integer
I = Even Integer - 1 = Odd Integer
Page 2
JEE Main Previous Year Questions (2021-2026):
Binomial Theorem
(January 2026)
Q1: Given below are two statements :
Statement I : 25
13
+ 20
13
+ 8
13
+ 3
13
is divisible by 7.
Statement II : The integral part of (7 + 4v3)
25
is an odd number.
In the light of the above statements, choose the correct answer from the options given
below :
(a) Statement I is false but Statement II is true
(b) Both Statement I and Statement II are false
(c) Both Statement I and Statement II are true
(d) Statement I is true but Statement II is false
Ans: (c)
Sol:
Statement I: 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7.
Key concept : If n is odd, xn + yn = (x + y)(xn ?¹ - xn ?²y + xn ?³y² - · · · - xyn ?² + yn ?¹) So, xn + yn is
divisible by x + y.
In the given statement :
25¹³ + 3¹³ is divisible by 25 + 3 = 28.
25¹³ + 3¹³ is also divisible by 7 because 28 is divisible by 7.
So, 25¹³ + 3¹³ = 7 · I 1..........(1) ( I 1 is a positive integer).
Similarly :
20¹³ + 8¹³ is divisible by 20 + 8 = 28.
20¹³ + 8¹³ is divisible by 7.
So, 20¹³ + 8¹³ = 7 · I 2 ..........(2) ( I 2 is a positive integer).
Add (1) & (2) :
25¹³ + 3¹³ + 20¹³ + 8¹³ = 7(I 1 + I 2)
So, 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7. Statement I is true.
Statement II: The integral part of (7 + 4v3)² 5 is an odd number.
Let X = (7 + 4v3)² 5. Let I be the integral part and f be the fractional part ( $0
Adding the two expansions:
(7 + 4v3)² 5 + (7 - 4v3)² 5 = I + f + f'
Using the binomial expansion (a + b)n + (a - b)n = 2[an + (n 2)an ?²b² + . . .], we see that the sum is
always an even integer because of the factor of 2.
I + f + f' = Even Integer
Since I is an integer, f + f' must also be an integer. Given 0 < f < 1 and 0 < f' < 1, the only
possible integer value for their sum is f + f' = 1.
I + 1 = Even Integer
I = Even Integer - 1 = Odd Integer
The integral part I is indeed an odd number. Statement II is True.
Q2: The sum of the coefficients of x
499
and x
500
in (1 + x)
1000
+ x (1 + x)
999
+ x
2
(1 + x)
998
+ … +
x 1000 is:
(a)
1002
C
501
(b)
1001
C
501
(c)
1000
C
501
(d)
1002
C
500
Ans: (d)
Sol:
Let
S = (1 + x)¹ ° ° ° + x(1 + x) ? ? ? + x²(1 + x) ? ? 8 + · · · + x¹ ° ° °
Notice that this is a Geometric Progression (GP) with:
First term (a): (1 + x)¹ ° ° °
Common ratio (r) : x/(1+x)
Number of terms (n): 1001
The sum of a GP is given by Substituting our values:
Simplify the denominator:
S = (1 + x)¹ ° °¹ - x¹ ° °¹
Now we need the coefficients of x 4 ? ? and x5 ° ° in the simplified expression (1 + x)¹ ° °¹ - x¹ ° °¹.
Since x¹ ° °¹ only affects the term with power 1001, we only look at (1 + x)¹ ° °¹.
In the binomial expansion (1 + x)n
Coefficient of x? is nC?
Coefficient of x 4 ? ? in S :
¹ ° °¹C 4 9 9
Coefficient of x 5 ° ° in S :
¹ ° °¹C 5 0 0 (The term x¹ ° °¹ does not contribute.)
Sum of coefficients
¹ ° °¹C 4 9 9 + ¹ ° °¹C 5 0 0 = ¹ ° °²C 5 0 0
[Using pascal's identity nC? + nC? ? 1 = n ?¹C? ? 1]
Q3: Let up to 13 terms. If 13 S = 2
k
/n! , k ? N ,
then n + k is equal to
Page 3
JEE Main Previous Year Questions (2021-2026):
Binomial Theorem
(January 2026)
Q1: Given below are two statements :
Statement I : 25
13
+ 20
13
+ 8
13
+ 3
13
is divisible by 7.
Statement II : The integral part of (7 + 4v3)
25
is an odd number.
In the light of the above statements, choose the correct answer from the options given
below :
(a) Statement I is false but Statement II is true
(b) Both Statement I and Statement II are false
(c) Both Statement I and Statement II are true
(d) Statement I is true but Statement II is false
Ans: (c)
Sol:
Statement I: 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7.
Key concept : If n is odd, xn + yn = (x + y)(xn ?¹ - xn ?²y + xn ?³y² - · · · - xyn ?² + yn ?¹) So, xn + yn is
divisible by x + y.
In the given statement :
25¹³ + 3¹³ is divisible by 25 + 3 = 28.
25¹³ + 3¹³ is also divisible by 7 because 28 is divisible by 7.
So, 25¹³ + 3¹³ = 7 · I 1..........(1) ( I 1 is a positive integer).
Similarly :
20¹³ + 8¹³ is divisible by 20 + 8 = 28.
20¹³ + 8¹³ is divisible by 7.
So, 20¹³ + 8¹³ = 7 · I 2 ..........(2) ( I 2 is a positive integer).
Add (1) & (2) :
25¹³ + 3¹³ + 20¹³ + 8¹³ = 7(I 1 + I 2)
So, 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7. Statement I is true.
Statement II: The integral part of (7 + 4v3)² 5 is an odd number.
Let X = (7 + 4v3)² 5. Let I be the integral part and f be the fractional part ( $0
Adding the two expansions:
(7 + 4v3)² 5 + (7 - 4v3)² 5 = I + f + f'
Using the binomial expansion (a + b)n + (a - b)n = 2[an + (n 2)an ?²b² + . . .], we see that the sum is
always an even integer because of the factor of 2.
I + f + f' = Even Integer
Since I is an integer, f + f' must also be an integer. Given 0 < f < 1 and 0 < f' < 1, the only
possible integer value for their sum is f + f' = 1.
I + 1 = Even Integer
I = Even Integer - 1 = Odd Integer
The integral part I is indeed an odd number. Statement II is True.
Q2: The sum of the coefficients of x
499
and x
500
in (1 + x)
1000
+ x (1 + x)
999
+ x
2
(1 + x)
998
+ … +
x 1000 is:
(a)
1002
C
501
(b)
1001
C
501
(c)
1000
C
501
(d)
1002
C
500
Ans: (d)
Sol:
Let
S = (1 + x)¹ ° ° ° + x(1 + x) ? ? ? + x²(1 + x) ? ? 8 + · · · + x¹ ° ° °
Notice that this is a Geometric Progression (GP) with:
First term (a): (1 + x)¹ ° ° °
Common ratio (r) : x/(1+x)
Number of terms (n): 1001
The sum of a GP is given by Substituting our values:
Simplify the denominator:
S = (1 + x)¹ ° °¹ - x¹ ° °¹
Now we need the coefficients of x 4 ? ? and x5 ° ° in the simplified expression (1 + x)¹ ° °¹ - x¹ ° °¹.
Since x¹ ° °¹ only affects the term with power 1001, we only look at (1 + x)¹ ° °¹.
In the binomial expansion (1 + x)n
Coefficient of x? is nC?
Coefficient of x 4 ? ? in S :
¹ ° °¹C 4 9 9
Coefficient of x 5 ° ° in S :
¹ ° °¹C 5 0 0 (The term x¹ ° °¹ does not contribute.)
Sum of coefficients
¹ ° °¹C 4 9 9 + ¹ ° °¹C 5 0 0 = ¹ ° °²C 5 0 0
[Using pascal's identity nC? + nC? ? 1 = n ?¹C? ? 1]
Q3: Let up to 13 terms. If 13 S = 2
k
/n! , k ? N ,
then n + k is equal to
(a) 50
(b) 52
(c) 49
(d) 51
Ans: (c)
Sol:
multiply in numerator and denominator by 26 !
Lets find 13th term lower subscript are in A.P with, common difference = 2
It is given that
substitute value of S
Page 4
JEE Main Previous Year Questions (2021-2026):
Binomial Theorem
(January 2026)
Q1: Given below are two statements :
Statement I : 25
13
+ 20
13
+ 8
13
+ 3
13
is divisible by 7.
Statement II : The integral part of (7 + 4v3)
25
is an odd number.
In the light of the above statements, choose the correct answer from the options given
below :
(a) Statement I is false but Statement II is true
(b) Both Statement I and Statement II are false
(c) Both Statement I and Statement II are true
(d) Statement I is true but Statement II is false
Ans: (c)
Sol:
Statement I: 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7.
Key concept : If n is odd, xn + yn = (x + y)(xn ?¹ - xn ?²y + xn ?³y² - · · · - xyn ?² + yn ?¹) So, xn + yn is
divisible by x + y.
In the given statement :
25¹³ + 3¹³ is divisible by 25 + 3 = 28.
25¹³ + 3¹³ is also divisible by 7 because 28 is divisible by 7.
So, 25¹³ + 3¹³ = 7 · I 1..........(1) ( I 1 is a positive integer).
Similarly :
20¹³ + 8¹³ is divisible by 20 + 8 = 28.
20¹³ + 8¹³ is divisible by 7.
So, 20¹³ + 8¹³ = 7 · I 2 ..........(2) ( I 2 is a positive integer).
Add (1) & (2) :
25¹³ + 3¹³ + 20¹³ + 8¹³ = 7(I 1 + I 2)
So, 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7. Statement I is true.
Statement II: The integral part of (7 + 4v3)² 5 is an odd number.
Let X = (7 + 4v3)² 5. Let I be the integral part and f be the fractional part ( $0
Adding the two expansions:
(7 + 4v3)² 5 + (7 - 4v3)² 5 = I + f + f'
Using the binomial expansion (a + b)n + (a - b)n = 2[an + (n 2)an ?²b² + . . .], we see that the sum is
always an even integer because of the factor of 2.
I + f + f' = Even Integer
Since I is an integer, f + f' must also be an integer. Given 0 < f < 1 and 0 < f' < 1, the only
possible integer value for their sum is f + f' = 1.
I + 1 = Even Integer
I = Even Integer - 1 = Odd Integer
The integral part I is indeed an odd number. Statement II is True.
Q2: The sum of the coefficients of x
499
and x
500
in (1 + x)
1000
+ x (1 + x)
999
+ x
2
(1 + x)
998
+ … +
x 1000 is:
(a)
1002
C
501
(b)
1001
C
501
(c)
1000
C
501
(d)
1002
C
500
Ans: (d)
Sol:
Let
S = (1 + x)¹ ° ° ° + x(1 + x) ? ? ? + x²(1 + x) ? ? 8 + · · · + x¹ ° ° °
Notice that this is a Geometric Progression (GP) with:
First term (a): (1 + x)¹ ° ° °
Common ratio (r) : x/(1+x)
Number of terms (n): 1001
The sum of a GP is given by Substituting our values:
Simplify the denominator:
S = (1 + x)¹ ° °¹ - x¹ ° °¹
Now we need the coefficients of x 4 ? ? and x5 ° ° in the simplified expression (1 + x)¹ ° °¹ - x¹ ° °¹.
Since x¹ ° °¹ only affects the term with power 1001, we only look at (1 + x)¹ ° °¹.
In the binomial expansion (1 + x)n
Coefficient of x? is nC?
Coefficient of x 4 ? ? in S :
¹ ° °¹C 4 9 9
Coefficient of x 5 ° ° in S :
¹ ° °¹C 5 0 0 (The term x¹ ° °¹ does not contribute.)
Sum of coefficients
¹ ° °¹C 4 9 9 + ¹ ° °¹C 5 0 0 = ¹ ° °²C 5 0 0
[Using pascal's identity nC? + nC? ? 1 = n ?¹C? ? 1]
Q3: Let up to 13 terms. If 13 S = 2
k
/n! , k ? N ,
then n + k is equal to
(a) 50
(b) 52
(c) 49
(d) 51
Ans: (c)
Sol:
multiply in numerator and denominator by 26 !
Lets find 13th term lower subscript are in A.P with, common difference = 2
It is given that
substitute value of S
n + K = 25 + 24 = 49
Q4: The sum of all possible values of n ? N, so that the coefficients of x, x
2
and x
3
in the
expansion of (1 + x
2
)
2
(1 + x)
n
, are in arithmetic progression is:
(a) 12
(b) 9
(c) 3
(d) 7
Ans: (b)
Sol:
(1 + x²)²(1 + xn)
(1 + x 4 + 2x²)(1 + x)n
Coeff of x = nC 1
Coeff of x² = nC 2 + 2 · nC 0
Coeff of x³ = nC 3 + 2 · nC 1
? Coeff of x, x², x³ ? AP
? 2(nC 2 + 2) = nC 1 + nC 3 + 2n
2nC 2 + 4 = nC 3 + 3n
? n³ - 9n² + 26n - 24 = 0
? n = 2, 3, 4
? Sum of all value of n is 9
Q5: The value of
(a)
(b)
(c)
Page 5
JEE Main Previous Year Questions (2021-2026):
Binomial Theorem
(January 2026)
Q1: Given below are two statements :
Statement I : 25
13
+ 20
13
+ 8
13
+ 3
13
is divisible by 7.
Statement II : The integral part of (7 + 4v3)
25
is an odd number.
In the light of the above statements, choose the correct answer from the options given
below :
(a) Statement I is false but Statement II is true
(b) Both Statement I and Statement II are false
(c) Both Statement I and Statement II are true
(d) Statement I is true but Statement II is false
Ans: (c)
Sol:
Statement I: 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7.
Key concept : If n is odd, xn + yn = (x + y)(xn ?¹ - xn ?²y + xn ?³y² - · · · - xyn ?² + yn ?¹) So, xn + yn is
divisible by x + y.
In the given statement :
25¹³ + 3¹³ is divisible by 25 + 3 = 28.
25¹³ + 3¹³ is also divisible by 7 because 28 is divisible by 7.
So, 25¹³ + 3¹³ = 7 · I 1..........(1) ( I 1 is a positive integer).
Similarly :
20¹³ + 8¹³ is divisible by 20 + 8 = 28.
20¹³ + 8¹³ is divisible by 7.
So, 20¹³ + 8¹³ = 7 · I 2 ..........(2) ( I 2 is a positive integer).
Add (1) & (2) :
25¹³ + 3¹³ + 20¹³ + 8¹³ = 7(I 1 + I 2)
So, 25¹³ + 20¹³ + 8¹³ + 3¹³ is divisible by 7. Statement I is true.
Statement II: The integral part of (7 + 4v3)² 5 is an odd number.
Let X = (7 + 4v3)² 5. Let I be the integral part and f be the fractional part ( $0
Adding the two expansions:
(7 + 4v3)² 5 + (7 - 4v3)² 5 = I + f + f'
Using the binomial expansion (a + b)n + (a - b)n = 2[an + (n 2)an ?²b² + . . .], we see that the sum is
always an even integer because of the factor of 2.
I + f + f' = Even Integer
Since I is an integer, f + f' must also be an integer. Given 0 < f < 1 and 0 < f' < 1, the only
possible integer value for their sum is f + f' = 1.
I + 1 = Even Integer
I = Even Integer - 1 = Odd Integer
The integral part I is indeed an odd number. Statement II is True.
Q2: The sum of the coefficients of x
499
and x
500
in (1 + x)
1000
+ x (1 + x)
999
+ x
2
(1 + x)
998
+ … +
x 1000 is:
(a)
1002
C
501
(b)
1001
C
501
(c)
1000
C
501
(d)
1002
C
500
Ans: (d)
Sol:
Let
S = (1 + x)¹ ° ° ° + x(1 + x) ? ? ? + x²(1 + x) ? ? 8 + · · · + x¹ ° ° °
Notice that this is a Geometric Progression (GP) with:
First term (a): (1 + x)¹ ° ° °
Common ratio (r) : x/(1+x)
Number of terms (n): 1001
The sum of a GP is given by Substituting our values:
Simplify the denominator:
S = (1 + x)¹ ° °¹ - x¹ ° °¹
Now we need the coefficients of x 4 ? ? and x5 ° ° in the simplified expression (1 + x)¹ ° °¹ - x¹ ° °¹.
Since x¹ ° °¹ only affects the term with power 1001, we only look at (1 + x)¹ ° °¹.
In the binomial expansion (1 + x)n
Coefficient of x? is nC?
Coefficient of x 4 ? ? in S :
¹ ° °¹C 4 9 9
Coefficient of x 5 ° ° in S :
¹ ° °¹C 5 0 0 (The term x¹ ° °¹ does not contribute.)
Sum of coefficients
¹ ° °¹C 4 9 9 + ¹ ° °¹C 5 0 0 = ¹ ° °²C 5 0 0
[Using pascal's identity nC? + nC? ? 1 = n ?¹C? ? 1]
Q3: Let up to 13 terms. If 13 S = 2
k
/n! , k ? N ,
then n + k is equal to
(a) 50
(b) 52
(c) 49
(d) 51
Ans: (c)
Sol:
multiply in numerator and denominator by 26 !
Lets find 13th term lower subscript are in A.P with, common difference = 2
It is given that
substitute value of S
n + K = 25 + 24 = 49
Q4: The sum of all possible values of n ? N, so that the coefficients of x, x
2
and x
3
in the
expansion of (1 + x
2
)
2
(1 + x)
n
, are in arithmetic progression is:
(a) 12
(b) 9
(c) 3
(d) 7
Ans: (b)
Sol:
(1 + x²)²(1 + xn)
(1 + x 4 + 2x²)(1 + x)n
Coeff of x = nC 1
Coeff of x² = nC 2 + 2 · nC 0
Coeff of x³ = nC 3 + 2 · nC 1
? Coeff of x, x², x³ ? AP
? 2(nC 2 + 2) = nC 1 + nC 3 + 2n
2nC 2 + 4 = nC 3 + 3n
? n³ - 9n² + 26n - 24 = 0
? n = 2, 3, 4
? Sum of all value of n is 9
Q5: The value of
(a)
(b)
(c)
(d)
Ans: (b)
Sol:
Q6: Let C
r
denote the coefficient of x
r
in the binomial expansion of (1 + x)
n
, n ?N, 0 = r = n.
If , then the
value of equals.
(a) 675
(b) 580
(c) 525
(d) 650
Ans: (a)
Sol:
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