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JEE Advanced 2025Paper 2
Exam
JEE Advanced
Year
2025
Paper
Paper 2
Subject
Mathematics
Chapter
Application of Derivatives

JEE Advanced 2025 · Paper 2 · Mathematics · Application of Derivatives

Let ℝ denote the set of all real numbers. Let f: ℝ arrow ℝ be...

Let R\mathbb{R} denote the set of all real numbers. Let f:R→Rf: \mathbb{R} \rightarrow \mathbb{R} be defined by f(x)=f(x)=\begin{cases}\frac{6 x+\sin x}{2 x+\sin x} & \text{ if } x \neq 0 \\ \frac{7}{3} & \text{ if } x=0\end{cases}$$ Then which of the following statements is (are) TRUE?Let ℝ denote the set of all real numbers. Let f: ℝ arrow ℝ be defined by f(x)= cases (6 x+ x)/(2 x+ x) & if x ≠ 0Let ℝ denote the set of all real numbers. Let f: ℝ arrow ℝ be defined by f(x)= cases (6 x+ x)/(2 x+ x) & if x ≠ 0

Options

  1. AThe point x=0x=0 is a point of local maxima of ff
  2. BThe point x=0x=0 is a point of local minima of ff
  3. CNumber of points of local maxima of ff in the interval [π,6π][\pi, 6 \pi] is 3
  4. DNumber of points of local minima of ff in the interval [2π,4π][2 \pi, 4 \pi] is 1

Correct answer

B. The point x=0x=0 is a point of local minima of ff

Step-by-step solution

Let ℝ denote the set of all real numbers. Let f: ℝ arrow ℝ be defined by f(x)= cases (6 x+ x)/(2 x+ x) & if x ≠ 0
since 3>73⇒3>f(0)3>\frac{7}{3} \Rightarrow 3>f(0) ⇒x=0\Rightarrow x=0 is local minima ....option (B) is correct Now, f(x)=6x+sin⁡x2x+sin⁡x=1+4x2x+sin⁡xf′(x)=4[(2x+sin⁡x)⋅1−x(2+cos⁡x)](2x+sin⁡x)2=4(sin⁡x−xcos⁡x)(2x+sin⁡x)2=4cos⁡x(tan⁡x−x)(2x+sin⁡x)2\begin{aligned} & f(x)=\frac{6 x+\sin x}{2 x+\sin x}=1+\frac{4 x}{2 x+\sin x} \\ & f^{\prime}(x)=\frac{4[(2 x+\sin x) \cdot 1-x(2+\cos x)]}{(2 x+\sin x)^2}=\frac{4(\sin x-x \cos x)}{(2 x+\sin x)^2} \\ & =\frac{4 \cos x(\tan x-x)}{(2 x+\sin x)^2} \end{aligned}Let ℝ denote the set of all real numbers. Let f: ℝ arrow ℝ be defined by f(x)= cases (6 x+ x)/(2 x+ x) & if x ≠ 0
Options (C) \& (D) are also correct.
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