JEE Main & Advanced Mathematics Determinants & Matrices Question Bank Expansion of determinants, Solution of equation in the form of determinants and properties of determinants

  • question_answer
    \[\left| \,\begin{matrix}    b+c & a & a  \\    b & c+a & b  \\    c & c & a+b  \\ \end{matrix}\, \right|=\]        [Roorkee 1980; RPET 1997, 99; KCET 1999; MP PET 2001]

    A) \[abc\]

    B) \[2abc\]

    C) \[3abc\]

    D) \[4abc\]

    Correct Answer: D

    Solution :

      \[\left| \,\begin{matrix}    b+c & a & a  \\    b & c+a & b  \\    c & c & a+b  \\ \end{matrix}\, \right|\,=\,\left| \,\begin{matrix}    0 & -2c & -2b  \\    b & c+a & b  \\    c & c & a+b  \\ \end{matrix}\, \right|\] {by \[{{R}_{1}}\to {{R}_{1}}-({{R}_{2}}+{{R}_{3}})\}\] = \[2c.b(a+b-c)\,-2b.c(b-c-a)\,=4abc\].


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