10th Class Mathematics Polynomials Question Bank Case Based MCQs - Polynomials

  • question_answer
    The zeroes of the quadratic polynomial \[4\sqrt{3}{{x}^{2}}+5x-2\sqrt{3}\] are

    A) \[\frac{2}{\sqrt{3}},\frac{\sqrt{3}}{4}\]

    B) \[-\frac{2}{\sqrt{3}},\frac{\sqrt{3}}{4}\]

    C) \[\frac{2}{\sqrt{3}},-\frac{\sqrt{3}}{4}\]

    D) \[-\frac{2}{\sqrt{3}},-\frac{\sqrt{3}}{4}\]

    Correct Answer: B

    Solution :

    Let \[p\left( x \right)=4\sqrt{3}{{x}^{2}}+5x-2\sqrt{3}\]
    \[=4\sqrt{3}{{x}^{2}}+\left( 8-3 \right)x-2\sqrt{3}\]
    [by splitting middle term]
    \[=4\sqrt{3}{{x}^{2}}+8x-3x-2\sqrt{3}\]
    \[=4x\left( \sqrt{3}x+2 \right)-\sqrt{3}\left( \sqrt{3}x+2 \right)\]
    \[=\left( 4x-\sqrt{3} \right)\left( \sqrt{3}x+2 \right)\]
    For finding the zeroes, put \[p\left( x \right)=0\]
    \[\therefore \,\,\,\left( 4x-\sqrt{3} \right)\left( \sqrt{3}x+2 \right)=0\]
    \[\Rightarrow \,\,\,\,4x-\sqrt{3}=0\] and \[\sqrt{3}x+2=0\]
    \[\Rightarrow \,\,\,x=\frac{\sqrt{3}}{4}\] and \[x=-\frac{2}{\sqrt{3}}\]


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