Ratio of coefficient of terms {x^{n - r}}{a^r} and {x^r}{a^{n - r}} in binomial expansion of {(x + a

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7.Binomial Theorem

easy

The ratio of the coefficient of terms ${x^{n - r}}{a^r}$and ${x^r}{a^{n - r}}$ in the binomial expansion of ${(x + a)^n}$ will be

A

$x:a$

B

$n:r$

C

$x:n$

D

None of these

Solution

(d) Ratio of coefficient of ${x^{n – r}}{a^r} $ and ${x^r}{a^{n – r}}$ is

$= \frac{{^n{C_r}}}{{^n{C_{n – r}}}} = \frac{{^n{C_r}}}{{^n{C_r}}} = \frac{1}{1}$

Standard 11

Mathematics

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