7th Class Mathematics Algebraic Expressions Question Bank Algebraic Expressions

  • question_answer
    If\[m=\frac{ab}{a-b}\], then b equals.......

    A) \[\frac{m(a-b)}{a}\]                   

    B) \[\frac{ab-ma}{m}\]

    C) \[\frac{1}{1+1}\]                                  

    D) \[\frac{ma}{m+a}\]

    Correct Answer: D

    Solution :

    (d) \[m=\frac{ab}{a-b}\] \[\Rightarrow \]\[\frac{1}{m}=\frac{a-b}{ab}\Rightarrow \frac{1}{m}=\frac{1}{b}-\frac{1}{a}\Rightarrow \frac{1}{b}=\frac{1}{m}+\frac{1}{a}\] \[\Rightarrow \]\[\frac{1}{b}=\frac{a+m}{ma}\Rightarrow b=\frac{ma}{m+a}\]


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