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Question: Answered & Verified by Expert
Assuming \(|x|\) to be so small, that \(x^2\) and higher powers of \(x\) can be neglected, then \(\frac{\sqrt{1+x}+(1-x)^{3 / 2}}{(1+x)+\sqrt{1+x}}=\)
MathematicsBinomial TheoremAP EAMCETAP EAMCET 2020 (17 Sep Shift 1)
Options:
  • A \(1+\frac{5 x}{4}\)
  • B \(1-\frac{5 x}{4}\)
  • C \(1+\frac{4 x}{5}\)
  • D \(1-\frac{4 x}{5}\)
Solution:
2836 Upvotes Verified Answer
The correct answer is: \(1-\frac{5 x}{4}\)
Given, \(|x|\) is very small, \(x^2\) is negligible
\(\begin{aligned}
& \frac{\sqrt{1+x}+(1-x)^{3 / 2}}{(1+x)+\sqrt{1+x}}=\frac{1+\frac{1}{2} x+1-\frac{3}{2} x}{1+x+1+\frac{x}{2}} \\
& =\frac{2-x}{2+\frac{3 x}{2}}=\frac{4-2 x}{4+3 x}=\frac{(4-2 x)(4-3 x)}{\left(16-9 x^2\right)} \\
& =\frac{16-20 x+6 x^2}{16-9 x^2}=\frac{16-20 x}{16}\left\{\because x^2 \text { negligible }\right\} \\
& =1-\frac{5 x}{4}
\end{aligned}\)

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