a) \(\sqrt 3 .\left( {\sqrt {192} - \sqrt {75} } \right)\)\( = \sqrt 3 .\left( {\sqrt {64.3} - \sqrt {25.3} } \right)\)\( = \sqrt 3 .\sqrt 3 \left( {\sqrt {64} - \sqrt {25} } \right)\)\( = 3.\left( {8 - 5} \right)\)\( = 9\)
b) \(\frac{{ - 3\sqrt {18} + 5\sqrt {50} - \sqrt {128} }}{{7\sqrt 2 }}\)\( = \frac{{ - 3.\sqrt {9.2} + 5.\sqrt {25.2} - \sqrt {64.2} }}{{7\sqrt 2 }}\)\( = \frac{{\sqrt 2 \left( { - 3\sqrt 9 + 5\sqrt {25} - \sqrt {64} } \right)}}{{7\sqrt 2 }}\)\( = \frac{ - 9 + 25 - 8}{7}\)\( = \frac{8}{7}\)
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