Q234 / 270 · NDA 2017 (Phase 1) · Mathematics

What is the maximum value of the function $f(x)=$ $4 \sin ^2 x+1 ?$

  • Correct answer
    A
    5
  • B
    3
  • C
    2
  • D
    1

Solution

We know, $-1 \leq \sin x \leq 1$ $\begin{aligned} & \Rightarrow 0 \leq \sin ^2 x \leq 1 \\ & \Rightarrow 0 \leq 4 \sin ^2 x \leq 4 \\ & \Rightarrow 1 \leq 4 \sin ^2 x+1 \leq 5 \end{aligned}$

Hence, the correct answer is option: 'A'.

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