10th Class Mathematics Related to Competitive Exam Question Bank Algebra

  • question_answer
    If sum and difference of two expressions is \[5{{x}^{2}}-x-4\] and \[{{x}^{2}}+9x-10\] respectively, then the expressions are

    A)  \[(4{{x}^{2}}+8x-6),(4{{x}^{2}}-10x+2)\]

    B)  \[(2{{x}^{2}}+4x-3),(3{{x}^{2}}-10x-6)\]

    C)  \[(3{{x}^{2}}+4x-7),(2{{x}^{2}}-5x+3)\]  

    D)  \[(3{{x}^{2}}+4x+7),(2{{x}^{2}}-5x-3)\]

    Correct Answer: C

    Solution :

     Let the two expressions are \[X\] and\[Y\], then by hypothesis,                 \[X+Y=5{{x}^{2}}-x-4\]                   ? (i) and        \[X-Y={{x}^{2}}+9x-10\]                ... (ii) Adding and subtracting both equations, we get                 \[2X=6{{x}^{2}}+8x-14\] or              \[X=3{{x}^{2}}+4x-7\] and        \[2Y=4{{x}^{2}}-10x+6\] or              \[Y=2{{x}^{2}}-5x+3\]


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