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If x = 2 + √3, y = 2 - √3, z = 1 then what is the value of $$\frac{x}{{yz}} + \frac{y}{{xz}} + \frac{z}{{xy}} + 2\left[ {\frac{1}{x} + \frac{1}{y} + \frac{1}{z}} \right]?$$
Answer & Solution
Correct Answer:
Option
A
$$\eqalign{
& x = 2 + \sqrt 3 \cr
& y = 2 - \sqrt 3 \cr
& z = 1 \cr
& \frac{x}{{yz}} + \frac{y}{{xz}} + \frac{z}{{xy}} + 2\left[ {\frac{1}{x} + \frac{1}{y} + \frac{1}{z}} \right] \cr
& = \frac{{{x^2} + {y^2} + {z^2}}}{{xyz}} + 2\left[ {\frac{1}{x} + \frac{1}{y} + \frac{1}{z}} \right] \cr
& = \frac{{{{\left( {2 + \sqrt 3 } \right)}^2} + {{\left( {2 - \sqrt 3 } \right)}^2} + {{\left( 1 \right)}^2}}}{{\left( {2 + \sqrt 3 } \right)\left( {2 - \sqrt 3 } \right)\left( 1 \right)}} + 2\left[ {\frac{1}{{\left( {2 + \sqrt 3 } \right)}} + \frac{1}{{\left( {2 - \sqrt 3 } \right)}} + 1} \right] \cr
& = \frac{{4 + 3 + 4\sqrt 3 + 4 + 3 - 4\sqrt 3 + 1}}{1} + 2\left[ {2 - \sqrt 3 + 2 + \sqrt 3 + 1} \right] \cr
& = 15 + 10 \cr
& = 25 \cr} $$
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