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The number of solutions of $12 \cos^{3} x - 7 \cos^{2} x + 4 \cos x = 9$ is

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Correct option is C

The given equation is (cos⁡x−1)12cos2⁡x+5cos⁡x+9=0⇒cos⁡x=1 only as the other factor gives imaginary roots⇒ x=2nπ,n∈ZHence, it has infinite solutions as n∈Z

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The number of solutions of 12cos3⁡x−7cos2⁡x+4cos⁡x=9 is

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The number of solutions of $12 \cos^{3} x - 7 \cos^{2} x + 4 \cos x = 9$ is