7th Class Mathematics Algebraic Expressions Question Bank Algebra

  • question_answer
    Product of \[\left( \frac{3a}{4}-\frac{2b}{3} \right)\] and \[\left( \frac{3a}{4}+\frac{2b}{3} \right)\] is

    A)  \[\frac{9}{16}{{a}^{2}}-\frac{4}{9}{{b}^{2}}\]

    B)  \[\frac{9}{16}{{a}^{2}}-\frac{6}{12}{{b}^{2}}\]

    C)  \[\frac{9}{16}{{a}^{2}}-\frac{6}{12}{{b}^{2}}-\frac{6}{12}{{b}^{2}}-\frac{4}{9}ab\]

    D)  \[\frac{6}{12}{{a}^{2}}-\frac{9}{16}{{b}^{2}}\]

    Correct Answer: A

    Solution :

     \[\left( \frac{3a}{4}-\frac{2b}{3} \right)\left( \frac{3a}{4}+\frac{2b}{3} \right)\] \[=\frac{9}{16}{{a}^{2}}+\left( \frac{3a}{4} \right)\left( \frac{2b}{3} \right)-\left( \frac{2b}{3} \right)\left( \frac{3a}{4} \right)-\frac{4}{9}{{b}^{2}}\] \[=\frac{9}{16}{{a}^{2}}-\frac{4}{9}{{b}^{2}}\]


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