10th Class Mathematics Quadratic Equations Question Bank Quadratic Equations

  • question_answer
    In the Maths Olympiad of 2020 at Animal Planet, two representatives from the donkey's side, while solving a quadratic equation, committed the following mistakes.
    (i)  One of them made a mistake in the constant term and got the roots as 5 I and 9.                           
    (ii) Another one committed an error in the coefficient of x and he got the roots as 12 and 4.
    But in the meantime, they realized that they are wrong and they managed to get it right jointly. Find the quadratic equation.        

    A)  \[{{x}^{2}}+4x+14=0\]                    

    B)                     \[2{{x}^{2}}+7x-24=0\]                    

    C)                     \[{{x}^{2}}\text{-}14x+48=0\]

    D)                     \[3{{x}^{2}}-17x+52=0\]

    Correct Answer: C

    Solution :

    For 1st one, Let the equation be \[{{x}^{2}}+ax+b=0\] Since roots are 5 and 9 \[\therefore \]  \[a=-14\]and \[b=45\] For 2nd one, Let the equation be \[{{x}^{2}}+px+q=0\] Since roots are 12 and 4. \[p=-16\]and \[q=48\] Now, according to the question, b and p both are wrong. Therefore, the correct equation would be \[{{x}^{2}}-14x+48=0\]


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