JAMIA 2022 — Mathematics PYQ
JAMIA | Mathematics | 2022In the expansion of (1+x)50 the sum of coefficients of odd powers of x is
Choose the correct answer:
- A.
250
- B.
0
- C.
249
(Correct Answer) - D.
251
249
Explanation
1. General Expansion
The binomial expansion of (1+x)n is:
(1+x)n=C0+C1x+C2x2+C3x3+⋯+Cnxn
2. Finding the Sum of All Coefficients
Put x=1:
(1+1)50=C0+C1+C2+C3+⋯+C50
250=C0+C1+C2+C3+⋯+C50 --- (Equation 1)
3. Finding the Alternating Sum
Put x=−1:
(1−1)50=C0−C1+C2−C3+⋯+C50
0=C0−C1+C2−C3+⋯+C50 --- (Equation 2)
4. Solve for Odd Powers
Subtract Equation 2 from Equation 1:
(C0+C1+C2+…)−(C0−C1+C2−…)=250−0
2(C1+C3+C5+⋯+C49)=250
Divide by 2:
C1+C3+C5+⋯+C49=2250
C1+C3+C5+⋯+C49=249
Final Answer:
The sum of coefficients of odd powers of x is 249.
Explanation
1. General Expansion
The binomial expansion of (1+x)n is:
(1+x)n=C0+C1x+C2x2+C3x3+⋯+Cnxn
2. Finding the Sum of All Coefficients
Put x=1:
(1+1)50=C0+C1+C2+C3+⋯+C50
250=C0+C1+C2+C3+⋯+C50 --- (Equation 1)
3. Finding the Alternating Sum
Put x=−1:
(1−1)50=C0−C1+C2−C3+⋯+C50
0=C0−C1+C2−C3+⋯+C50 --- (Equation 2)
4. Solve for Odd Powers
Subtract Equation 2 from Equation 1:
(C0+C1+C2+…)−(C0−C1+C2−…)=250−0
2(C1+C3+C5+⋯+C49)=250
Divide by 2:
C1+C3+C5+⋯+C49=2250
C1+C3+C5+⋯+C49=249
Final Answer:
The sum of coefficients of odd powers of x is 249.

