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6th Class Mental Ability Algebra Question Bank Algebra

  • question_answer
    Subtract the following: \[{{\mathbf{x}}^{\mathbf{3}}}-\mathbf{3}{{\mathbf{x}}^{\mathbf{2}}}-\mathbf{5x}+\mathbf{4}\]from \[\mathbf{3}{{\mathbf{x}}^{\mathbf{3}}}-{{\mathbf{x}}^{\mathbf{2}}}+\mathbf{2x}-\mathbf{4}.\]

    A) \[2{{x}^{3}}+2{{x}^{2}}+7x-8\]     

    B) \[-2{{x}^{5}}-7x+8\]

    C) \[2{{x}^{3}}-2{{x}^{2}}-4x-8\]         

    D) All of these

    E) None of these

    Correct Answer: A

    Solution :

    Explanation Option [a] is correct. \[3{{x}^{3}}-{{x}^{2}}+\mathbf{2x}-\mathbf{4}-\left( {{x}^{3}}-3{{x}^{2}}-5x+4 \right)\] \[=3{{x}^{3}}-{{x}^{2}}+2x-4-{{x}^{3}}+3{{x}^{2}}+5x-4\] \[=2{{x}^{3}}+2{{x}^{2}}+7x-8.\]


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