8th Class Mathematics Algebraic Expressions Question Bank Algebraic Expressions and Identities

  • question_answer
    Simplify: \[{{\left[ 2{{x}^{2}}-\frac{1}{400}{{y}^{2}} \right]}^{2}}-{{\left[ 2{{x}^{2}}+\frac{1}{400}{{y}^{2}} \right]}^{2}}\]

    A)  \[-\frac{{{x}^{2}}{{y}^{2}}}{40}\]                  

    B)  \[-\frac{{{x}^{2}}{{y}^{2}}}{50}\]      

    C)  \[\frac{xy}{50}\]                   

    D)         \[-\frac{{{x}^{2}}{{y}^{2}}}{5}\]        

    Correct Answer: B

    Solution :

    \[{{\left[ 2{{x}^{2}}-\frac{1}{400}{{y}^{2}} \right]}^{2}}-{{\left[ 2{{x}^{2}}+\frac{1}{400}{{y}^{2}} \right]}^{2}}\] \[=\left[ 2{{x}^{2}}-\frac{1}{400}{{y}^{2}}+2{{x}^{2}}+\frac{1}{400}{{y}^{2}} \right]\]             \[\times \left[ 2{{x}^{2}}-\frac{1}{400}{{y}^{2}}-2{{x}^{2}}-\frac{1}{400}{{y}^{2}} \right]\] \[=[4{{x}^{2}}]\left[ -\frac{2}{400}{{y}^{2}} \right]=\frac{-8{{x}^{2}}{{y}^{2}}}{400}=\frac{{{x}^{2}}{{y}^{2}}}{50}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner