COMEDK · Maths · 7. Binomial Theorem
Find \({ }^n C_{21}\), if \({ }^n C_{10}={ }^n C_{12}\)
- A 1
- B 21
- C 22
- D 2
Answer & Solution
Correct Answer
(C) 22
Step-by-step Solution
Detailed explanation
We know that if \({ }^n C_x={ }^n C_y\), then either \(x=y\) or \(x+y=n\) Since, \({ }^n C_{10}={ }^n C_{12}\)…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Maths
- The angle between the circles
\(\begin{aligned}
&x^{2}+y^{2}+4 x+2 y+1=0 \text { and } \\
&x^{2}+y^{2}-2 x+6 y-6=0 \text { is }
\end{aligned}\)COMEDK 2012 Easy - If the matrix \(M = \begin{bmatrix} x+5 & a & -4 \\ -2 & 0 & b \\ c & 6 & y+1 \end{bmatrix}\) is a skew symmetric matrix, the value of the expression \(ab + c^2 - xy\) is:COMEDK 2026 Easy
- If \(A=\left[\begin{array}{ll}2 & 2 \\ 3 & 4\end{array}\right]\), then \(A^{-1}\) equals toCOMEDK 2023 Easy
- Evaluate : \(\cos ^{-1}\left[\cos \left(-680^{\circ}\right)\right]+\sin ^{-1}\left[\sin \left(-600^{\circ}\right)\right]-\cos ^{-1}\left(\sin 270^{\circ}\right)\)COMEDK 2024 Medium
- A spherical balloon is being inflated at the rate of \(35 \mathrm{~cm} / \mathrm{min}\). When its radius is \(7 \mathrm{~cm}\), its surface area increases at the rate ofCOMEDK 2014 Easy
- The derivative of \(y = \sin^2\left[\cot^{-1}\left(\sqrt{\dfrac{1-x}{1+x}}\right)\right]\) isCOMEDK 2026 Medium
More PYQs from COMEDK
- \(\text { Find }{ }^n C_{21} \text {, if }{ }^n C_{10}={ }^n C_{12}\)COMEDK 2023 Easy
- At Constant volume, the heat required to raise the temperature of \(4.48 \mathrm{~L}\) of an ideal gas at STP by \(15^{\circ} \mathrm{C}\) is 12.0 calories.
The \(\mathrm{C_p}\) of the gas is _____________
\((\mathrm{R}=2 \mathrm{~Cal} \mathrm{~kg}^{-1} \mathrm{~mol}^{-1})\)COMEDK 2024 Medium - The mass density of a nucleus varies with mass number \(A\) asCOMEDK 2023 Easy
- A uniform chain of length \(L\) is lying partly on a table, the remaining part hanging down from the edge of the table. If the coefficient of friction between the chain and the table is \(0.5\), what is the minimum length of the chain that should lie on the table, to prevent the chain from slipping down to the ground?COMEDK 2015 Hard
- An object is placed 25 cm in front of a fully silvered concave mirror of focal length 15 cm. A plane mirror is placed 35 cm behind the concave mirror on the side opposite to the object. The final image after reflection first from the concave mirror and then from the plane mirror is formed at:COMEDK 2026 Medium
- An organic compound which produces a bluish green flame when heated on a copper wire isCOMEDK 2012 Medium