JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Fundamental Integration

  • question_answer
    \[\int_{{}}^{{}}{\frac{\cos 2x-\cos 2\alpha }{\cos x-\cos \alpha }}dx=\] [MP PET 1994]

    A)            \[2[\sin x+x\cos \alpha ]+c\]

    B)            \[2[\sin x+\sin \alpha ]+c\]

    C)            \[2[-\sin x+x\cos \alpha ]+c\]

    D)            \[-2[\sin x+\sin \alpha ]+c\]

    Correct Answer: A

    Solution :

               \[\int_{{}}^{{}}{\frac{\cos 2x-\cos 2\alpha }{\cos x-\cos \alpha }}\,dx=\int_{{}}^{{}}{\frac{2({{\cos }^{2}}x-{{\cos }^{2}}\alpha )}{\cos x-\cos \alpha }\,dx}\]                    \[=2\int_{{}}^{{}}{(\cos x+\cos \alpha )\,dx}=2(\sin x+x\cos \alpha )\].


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