Applications of Derivatives — Maths STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceMathsApplications of Derivatives3 Marks
Question
Verify Lagrange's mean value theorem for the function $f(x)=\sqrt{x+4}$ on the interval $[0,5]$.
✓
Answer
Given that $f(x)=\sqrt{x+4}$ The function $f(x)$ is continuous on the closed interval $[0,5]$ and differentiable on the open interval $(0,5)$, so the LMVT is applicable to the function. Differentiate (I) w. r.t.x. $f^{\prime}(x)=\frac{1}{2 \sqrt{x+4}}$ Let $a=0$ and $b=5$ From (I), $ \begin{aligned} & f(a)=f(0)=\sqrt{0+4}=2 \\ & f(b)=f(5)=\sqrt{5+4}=3 \end{aligned} $ Let $c \in(0,5)$ such that $ \begin{gathered} f^{\prime}(c)=\frac{f(b)-f(a)}{b-a} \\ \frac{1}{2 \sqrt{c+4}}=\frac{3-2}{5-0}=\frac{1}{5} \\ \therefore \sqrt{c+4}=\frac{5}{2} \Rightarrow c+4=\frac{25}{4} \therefore c=\frac{9}{4} \in(0,5) \end{gathered} $ Thus Lagrange's Mean Value Theorem is verified.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.