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Question: Answered & Verified by Expert
An approximate value of $\sqrt[4]{18}$ is
MathematicsApplication of DerivativesAP EAMCETAP EAMCET 2018 (23 Apr Shift 2)
Options:
  • A 2.0512
  • B 2.0425
  • C 2.0625
  • D 2.0834
Solution:
2922 Upvotes Verified Answer
The correct answer is: 2.0625
Let $y=f(x)=x^{1 / 4}$ and $x=16$ and $\Delta x=2$
So, $\Delta y=\left(\frac{d y}{d x}\right) \Delta x=\frac{1}{4}\left(x^{-3 / 4}\right) \Delta x$
at $\quad x=16$ and $\Delta x=2$
$$
\Delta y=\frac{1}{4} \times \frac{1}{8} \times 2=\frac{1}{16} \text { and } y=(16)^{1 / 4}=2
$$
So, $\quad y+\Delta y=2+\frac{1}{16}=2.0625$

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