CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    If p, q are the roots of\[a{{x}^{2}}-25x+c=0,\]then \[{{p}^{3}}{{q}^{3}}+{{p}^{2}}{{q}^{3}}+{{p}^{3}}{{q}^{2}}\]is equal to:

    A)  \[{{c}^{2}}\left( \frac{c+25}{{{a}^{3}}} \right)\]                 

    B)         \[{{c}^{3}}{{\left( \frac{c-25}{{{a}^{2}}} \right)}^{2}}\]   

    C)         \[\frac{b{{c}^{3}}}{{{a}^{3}}}\]                                 

    D)         \[\frac{b{{c}^{2}}}{a}\]

    E)         \[{{c}^{2}}\left( \frac{c-25}{{{a}^{3}}} \right)\]

    Correct Answer: A

    Solution :

    Since,\[p,q\]are the roots of the equation \[a{{x}^{2}}-25x+c=0\] \[\therefore \]  \[p+q=\frac{20}{a},pq=\frac{c}{a}\] \[{{p}^{3}}{{q}^{3}}+{{p}^{2}}{{q}^{3}}+{{p}^{3}}{{q}^{2}}\] \[\Rightarrow \]       \[{{p}^{2}}{{q}^{2}}(pq+p+q)\] \[\Rightarrow \]               \[{{p}^{2}}{{q}^{2}}(pq+p+q)\] \[\Rightarrow \]               \[\frac{{{c}^{2}}}{{{a}^{2}}}\left( \frac{c}{a}+\frac{25}{a} \right)=\frac{{{c}^{2}}(c+25)}{{{a}^{3}}}\]


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