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Question: The coefficient of \((2r + 3)\) in the expansion of \((r - 1)^{th}\) is....

The coefficient of (2r+3)(2r + 3) in the expansion of

(r−1)th(r - 1)^{th} is.

A

r=r =

B

(ab3+ba3)21\left( \sqrt[3]{\frac{a}{\sqrt{b}}} + \sqrt{\frac{b}{\sqrt[3]{a}}} \right)^{21}

C

(r+1)(r + 1)

D

(1+x)m(1 + x)^{m}

Answer

r=r =

Explanation

Solution

nC4nC_{4}

= nC4+nC2nC_{4} +^{n}C_{2} nC4+nC2+nC4.nC2nC_{4} +^{n}C_{2} +^{n}C_{4}.^{n}C_{2}

∴ Coefficient of nC4+nC2+nC1.nC2nC_{4} +^{n}C_{2} +^{n}C_{1}.^{n}C_{2}