If $\frac{1}{2} \le x \le 1$, then ${\cos ^{ - 1}}\left( {4{x^3} - 3x} \right){\rm{\;}}$ equals

JEE MATHEMATICS MCQ: INVERSE TRIGONOMETRY

1 Easy

1 of 1

Application +4 | -1

\frac{1}{2} \le x \le 1

, then

{\cos ^{ - 1}}\left( {4{x^3} - 3x} \right)\mathrm{\;}

equals

View answer and explanation

Correct option: A

3{\cos ^{ - 1}}x

Option A (

3{\cos ^{ - 1}}x

) is correct because by substituting

x = \cos \theta

, the expression simplifies to

{\cos ^{ - 1}}(\cos 3\theta)

, which equals

3{\cos ^{ - 1}}x

within the given interval.

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