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MHT CET · Maths · Application of Derivatives

The approximate value of \(f(x)=3 x^{2}+5 x+3\) at \(x=3 \cdot 02\) is

  1. A \(45.46\)
  2. B \(v=45 \cdot 46\)
  3. C \(44 \cdot 76\)
  4. D \(44 \cdot 46\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(v=45 \cdot 46\)

Step-by-step Solution

Detailed explanation

Given \(f(x)=3 x^{2}+5 x+3 \Rightarrow f^{\prime}(x)=6 x+5\)
Let \(\mathrm{a}=3, \mathrm{~h}=0.02\)
\(\therefore \mathrm{f}(\mathrm{a}) \quad=\mathrm{f}(3)=27+15+3=45\)
\(f^{\prime}(a)=f^{\prime}(3) \quad=18+5=23\)
We know that
\(
\begin{aligned}
\mathrm{f}(\mathrm{a}+\mathrm{h}) & \div \mathrm{f}(\mathrm{a})+\mathrm{hf}^{\prime}(\mathrm{a})\end{aligned}\)
\(=45+(0.02)(23)=45+0.46=45.46\)