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Match List-I with List-II

List-IList-II
(A) The maximum value of f(x)=sin⁡(3x)+6f(x) = \sin(3x) + 6(I) 2
(B) The maximum value of f(x)=−∣x+2∣+4f(x) = -\vert x + 2\vert + 4(II) 5
(C) The minimum value of f(x)=(3x+1)2+5f(x) = (3x + 1)^2 + 5(III) 7
(D) The minimum value of f(x)=2cos⁡x+4f(x) = 2 \cos x + 4(IV) 4

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

The range of sin⁡(3x)\sin(3x) is [−1,1][-1, 1], so:

−1≤sin⁡(3x)≤1-1 \leq \sin(3x) \leq 1

Maximum of f(x)=sin⁡(3x)+6f(x) = \sin(3x) + 6 occurs when sin⁡(3x)=1\sin(3x) = 1:

f(x)max⁡=1+6=7⟶(III)f(x)_{\max} = 1 + 6 = 7 \longrightarrow \textbf{(III)}


Since ∣x+2∣≥0|x + 2| \geq 0, we have −∣x+2∣≤0-|x + 2| \leq 0.

Maximum of f(x)=−∣x+2∣+4f(x) = -|x + 2| + 4 occurs when ∣x+2∣=0|x + 2| = 0, i.e. x=−2x = -2:

f(x)max⁡=0+4=4⟶(IV)f(x)_{\max} = 0 + 4 = 4 \longrightarrow \textbf{(IV)}


Since (3x+1)2≥0(3x + 1)^2 \geq 0, the minimum of f(x)=(3x+1)2+5f(x) = (3x + 1)^2 + 5 occurs when (3x+1)2=0(3x + 1)^2 = 0, i.e. x=−13x = -\dfrac{1}{3}:

f(x)min⁡=0+5=5⟶(II)f(x)_{\min} = 0 + 5 = 5 \longrightarrow \textbf{(II)}


The range of cos⁡x\cos x is [−1,1][-1, 1], so:

−2≤2cos⁡x≤2-2 \leq 2\cos x \leq 2

Minimum of f(x)=2cos⁡x+4f(x) = 2\cos x + 4 occurs when cos⁡x=−1\cos x = -1:

f(x)min⁡=2(−1)+4f(x)_{\min} = 2(-1) + 4

=−2+4= -2 + 4

=2⟶(I)= 2 \longrightarrow \textbf{(I)}


(A)→(III)(A) \rightarrow (III), (B)→(IV)(B) \rightarrow (IV), (C)→(II)(C) \rightarrow (II), (D)→(I)(D) \rightarrow (I)

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