JEE Main & Advanced JEE Main Paper (Held On 11-Jan-2019 Evening)

  • question_answer
    Let \[{{(x+10)}^{50}}+{{(x-10)}^{50}}={{a}_{0}}+{{a}_{1}}x+{{a}_{2}}{{x}^{2}}+\]\[...+{{a}_{50}}{{x}^{50}},\] for all\[x\in R;\]then \[\frac{{{a}_{2}}}{{{a}_{0}}}\]is equal to [JEE  Main Online Paper (Held on 11-jan-2019 Evening)]

    A) 12.00                           

    B) 12.75

    C) 12.25               

    D)   12.50

    Correct Answer: C

    Solution :

    Here, \[{{(x+10)}^{50}}+{{(x-10)}^{50}}={{a}_{0}}+{{a}_{1}}x\]\[+{{a}_{2}}{{x}^{2}}+...+{{a}_{50}}{{x}^{50}}\] \[\Rightarrow \]\[2{{[}^{50}}{{C}_{0}}{{x}^{50}}{{+}^{50}}{{C}_{2}}{{x}^{48}}{{10}^{2}}+...{{+}^{50}}{{C}_{48}}{{x}^{2}}{{10}^{48}}\]\[{{+}^{50}}{{C}_{50}}{{10}^{50}}=\]\[{{a}_{0}}+{{a}_{1}}x+{{a}_{2}}{{x}^{2}}+...+{{a}_{50}}{{x}^{50}}\] \[\Rightarrow \]\[{{a}_{0}}=2\times {{10}^{50}},{{a}_{2}}=2{{\times }^{50}}{{C}_{48}}{{10}^{48}}\] \[\therefore \]\[\frac{{{a}_{2}}}{{{a}_{0}}}=\frac{^{50}{{C}_{48}}}{{{10}^{2}}}=12.25\]


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