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    Find the value of xxx if x128=162x\frac{x}{\sqrt{128}} = \frac{\sqrt{162}}{x}128​x​=x162​​​
    Question

    Find the value of xx if x128=162x\frac{x}{\sqrt{128}} = \frac{\sqrt{162}}{x}

    A.

    144

    B.

    196

    C.

    14

    D.

    12

    Correct option is D

    Given: 

    x128=162x\frac{x}{\sqrt{128}} = \frac{\sqrt{162}}{x} 

    Solution:

    Multiply both sides of the equation by x128 x \cdot \sqrt{128}  to eliminate the fractions:

    x2=128162x^2 = \sqrt{128} \cdot \sqrt{162} 

    Simplify the Square Roots: 

    128\sqrt{128}  = 642=642=82 \sqrt{64 \cdot 2} = \sqrt{64} \cdot \sqrt{2} = 8\sqrt{2}  

    162=812=812=92 \sqrt{162} = \sqrt{81 \cdot 2} = \sqrt{81} \cdot \sqrt{2} = 9\sqrt{2}  

    Now, 

    x2=(82)(92)x^2 = (8\sqrt{2}) \cdot (9\sqrt{2}) 

    x2=8922x^2 = 8 \cdot 9 \cdot \sqrt{2} \cdot \sqrt{2} 

    x2=892=144x^2 = 8 \cdot 9 \cdot 2 = 144 

    x=144=12x = \sqrt{144} = 12 

    The value of x is 12

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