If the $1011^{\text {th }}$ term from the end in the binominal expansion of $\left(\frac{4 x}{5}-\frac{5}{2 x}\right)^{2022}$ is 1024 times $1011^{\text {th }}$R term from the beginning, then $|x|$ is equal to
Solution
$\mathrm{T}_{1011}$ from beginning $=\mathrm{T}_{1010+1}$
<br/><br/>$$
={ }^{2022} \mathrm{C}_{1010}\left(\frac{4 \mathrm{x}}{5}\right)^{1012}\left(\frac{-5}{2 \mathrm{x}}\right)^{1010}
$$
<br/><br/>$\mathrm{T}_{1011}$ from end
<br/><br/>$$
={ }^{2022} \mathrm{C}_{1010}\left(\frac{-5}{2 \mathrm{x}}\right)^{1012}\left(\frac{4 \mathrm{x}}{5}\right)^{1010}
$$
<br/><br/>$$
\begin{aligned}
& \text { Given : }{ }^{2022} \mathrm{C}_{1010}\left(\frac{-5}{2 \mathrm{x}}\right)^{1012}\left(\frac{4 \mathrm{x}}{5}\right)^{1010} \\\\
& =2^{10} \cdot{ }^{2022} \mathrm{C}_{1010}\left(\frac{-5}{2 \mathrm{x}}\right)^{1010}\left(\frac{4 \mathrm{x}}{5}\right)^{1012}
\end{aligned}
$$
<br/><br/>$$
\begin{aligned}
&\Rightarrow \left(\frac{-5}{2 x}\right)^2=2^{10}\left(\frac{4 x}{5}\right)^2 \\\\
&\Rightarrow x^4=\frac{5^4}{2^{16}} \\\\
& \Rightarrow |x|=\frac{5}{16}
\end{aligned}
$$
About this question
Subject: Mathematics · Chapter: Binomial Theorem · Topic: Binomial Expansion
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