Verified Solution • 2025–26 Session moderate

QJEEM24Ma578c: JEE Main 2024 Mathematics - Class 11 JEEM24Ma578c Solution: Let the range of the function be . If and ar respectively the…

Let the range of the function f(x)=12+sin⁡3x+cos⁡3x,x∈Rf(x)=\frac{1}{2+\sin 3 x+\cos 3 x}, x \in \mathbb{R} be [a,b][a, b] . If α\alpha and β\beta ar respectively the A.M. and the G.M. of aa and bb , then αβ\frac{\alpha}{\beta} is equal to

Multiple Choice Options

  • A π\pi
  • B π\sqrt{\pi}
  • C 2\sqrt{2}
  • D 2

Step-by-Step Verified Solution

amp;F(x)=12+sin⁡3x+cos⁡3x,x∈Ramp;sin⁡3x+cos⁡3x∈[−2,2]amp;2+sin⁡3x+cos⁡3x∈[2−2,2+2]amp;⇒12+sin⁡3x+cos⁡3x∈[12+2,12−2]amp;⇒a=12+2,b=12−2amp;α=a+b2=12+2+12−22amp;=42×2=1amp;β=ab=(12+2)×(12−2)amp;=12=12amp;⇒αβ=2\begin{aligned}& F(x)=\frac{1}{2+\sin 3 x+\cos 3 x}, x \in \mathbb{R} \\& \sin 3 x+\cos 3 x \in[-\sqrt{2}, \sqrt{2}] \\& 2+\sin 3 x+\cos 3 x \in[2-\sqrt{2}, 2+\sqrt{2}] \\& \Rightarrow \frac{1}{2+\sin 3 x+\cos 3 x} \in\left[\frac{1}{2+\sqrt{2}}, \frac{1}{2-\sqrt{2}}\right] \\& \Rightarrow a=\frac{1}{2+\sqrt{2}}, b=\frac{1}{2-\sqrt{2}} \\& \alpha=\frac{a+b}{2}=\frac{\frac{1}{2+\sqrt{2}}+\frac{1}{2-\sqrt{2}}}{2} \\& =\frac{4}{2 \times 2}=1 \\& \beta=\sqrt{a b}=\sqrt{\left(\frac{1}{2+\sqrt{2}}\right) \times\left(\frac{1}{2-\sqrt{2}}\right)} \\& =\sqrt{\frac{1}{2}}=\frac{1}{\sqrt{2}} \\& \Rightarrow \frac{\alpha}{\beta}=\sqrt{2} \\\end{aligned}

Related Learning Resources & Exam Preparation