If ${\left( {1 + x} \right)^{15}} = {a_0} + {a_1}x + . \ldots + {a_{15}}{x^{15}}$, then $\mathop \sum \limits_{r = 1}^{15} r\frac{{{a_r}}}{{{a_{r - 1}}}}$ is equal to

JEE MATHEMATICS MCQ: BINOMIAL THEOREM

1 Easy

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Application +4 | -1

{\left( {1 + x} \right)^{15}} = {a_0} + {a_1}x + . \ldots + {a_{15}}{x^{15}}

, then

\sum \limits_{r = 1}^{15} r\frac{{{a_r}}}{{{a_{r - 1}}}}

is equal to

View answer and explanation

Correct option: C

120

Option C (120) is correct because by expanding the binomial and simplifying the summation, the result equals 120.

Practice All Chapter MCQs →

\left({ }^{10} C_0\right)^2-\left({ }^{10} C_1\right)^2+\ldots-\left({ }^{10} C_9\right)^2+\left({ }^{10} C_{10}\right)^2

a

d

\left( {n + 1} \right)

a{C_0} - \left( {a + d} \right){C_1} + \left( {a + 2d} \right){C_2} - ... + ...

(1-x)^{201}\left(1+x+x^2\right)^{200}

\left(\frac{1}{x}+2 x\right)^n

{x^5}

\frac{{1 + {x^2}}}{{1 + x}},\left| x \right| < 1,

\left(\begin{array}{c}2 n+1 \\ 0\end{array}\right)+\left(\begin{array}{c}2 n+1 \\ 3\end{array}\right)+\left(\begin{array}{c}2 n+1 \\ 6\end{array}\right)+\ldots=170

n