JEE Main & Advanced Mathematics Binomial Theorem and Mathematical Induction Question Bank Properties of binomial coefficients

  • question_answer
    If \[{{(1+x-2{{x}^{2}})}^{6}}=1+{{a}_{1}}x+{{a}_{2}}{{x}^{2}}+....+{{a}_{12}}{{x}^{12}}\], then the expression \[{{a}_{2}}+{{a}_{4}}+{{a}_{6}}+....+{{a}_{12}}\]has the value [RPET 1986, 99; UPSEAT 2003]

    A) 32

    B) 63

    C) 64

    D) None of these

    Correct Answer: D

    Solution :

    \[{{(1+x-2{{x}^{2}})}^{6}}=1+{{a}_{1}}x+{{a}_{2}}{{x}^{2}}+....+{{a}_{12}}{{x}^{12}}\]. Putting \[x=1\] and x = ? 1 and adding the results 64 = 2(1+a2+a4+...)  \[\therefore \,\,\,{{a}_{2}}+{{a}_{4}}+{{a}_{6}}+....+{{a}_{12}}=31\].


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