10th Class Mathematics Solved Paper - Mathematics-2015 Delhi Term-II Set-I

  • question_answer
    If \[x=-\frac{1}{2},\] is a solution of the quadratic equation \[3{{x}^{2}}+2kx-3=0\]find the value of k.

    Answer:

    Since \[x=\frac{-1}{2}\] is a solution of \[3{{x}^{2}}+2kx-3=0\] it must satisfy the equation.
    \[\therefore 3\times {{\left( -\frac{1}{2} \right)}^{2}}+2k\left( -\frac{1}{2} \right)-3=0\]
                                        \[\frac{3}{4}-k-3=0\]
                                        \[k=\frac{3}{4}-3\]
                                        \[k=\frac{-9}{4}\]


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