JEE Main & Advanced Mathematics Differentiation Question Bank Differentiation by Substitution

  • question_answer
    If \[y={{({{x}^{2}}-1)}^{m}}\], then the \[{{(2m)}^{th}}\]differential coefficient of y is                                                     [MP PET 1987]

    A)            m

    B)            \[(2m)!\]

    C)            2m

    D)            m!

    Correct Answer: B

    Solution :

               Expanding binomially                    \[y={{({{x}^{2}}-1)}^{m}}{{=}^{m}}{{C}_{o}}{{x}^{2m}}{{+}^{m}}{{C}_{1}}{{x}^{2m-2}}(-1)+.......\]                    So on differentiating all the terms except first reduces to zero, therefore                    \[\frac{{{d}^{2m}}y}{d{{x}^{2m}}}{{=}^{m}}{{C}_{0}}2m\text{ }(2m-1)\text{ }(2m-2)....1=(2m)!\].


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