RAJASTHAN ­ PET Rajasthan PET Solved Paper-2004

  • question_answer
    If in the expansion of\[{{(x+a)}^{n}},\]the sum of odd terms is P and sum of even terms is Q, then the value of\[{{({{x}^{2}}-{{a}^{2}})}^{n}}\]is

    A)  \[{{P}^{2}}+{{Q}^{2}}\]

    B)  \[4PQ\]

    C)  \[{{P}^{2}}-{{Q}^{2}}\]

    D)  \[2P-2Q\]

    Correct Answer: C

    Solution :

     Since, in the expansion of\[{{(x+a)}^{n}},\]sum of odd terms is P and sum of even terms is Q. So,\[P+Q\]is the sum of total terms in this expansion. Similarly,\[P-Q\] is the sum of total terms in the expansion of\[{{(x-a)}^{n}}\]. \[\therefore \] \[P+Q={{(x+a)}^{n}}\] and       \[P-Q={{(x-a)}^{n}}\] \[\therefore \] \[{{(x+a)}^{n}}{{(x-a)}^{n}}=(P+Q)(P-Q)\] \[\Rightarrow \] \[{{({{x}^{2}}-{{a}^{2}})}^{n}}={{P}^{2}}-{{Q}^{2}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner