2. Solved Papers
  3. JEE Main & Advanced

JEE Main & Advanced JEE Main Paper (Held on 08-4-2019 Afternoon)

  • question_answer
    Let the number 2, b, c be in an A.P. and \[A=\left[ \begin{matrix}    1 & 1 & 1  \\    2 & b & c  \\    4 & {{b}^{2}} & {{c}^{2}}  \\ \end{matrix} \right].\]If det \[(A)\in [2,16],\]then c lies in the interval :    [JEE Main 8-4-2019 Afternoon]

    A) \[[2,3)\]                       

    B) \[(2+{{2}^{3/4}},4)\]

    C) \[[3,2+{{2}^{3/4}}]\]         

    D)   \[[4,6]\]

    Correct Answer: D

    Solution :

    put\[b=\frac{2+c}{2}\] in determinant of A \[|A|=\frac{{{c}^{3}}-6{{c}^{2}}+12c-8}{4}\in [2,16]\] \[\Rightarrow \]\[{{(c-2)}^{3}}\in [8,64]\]\[\Rightarrow \]\[c\in [4,6]\]


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