<PRE><B>Question 327672</B>
multipy 
sqrt7(sqrt3-sqrt7)
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= sqrt(21) - 7
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multiply and simplify 
sqrt(28a^9b) * sqrt(8a^10b^8)
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= sqrt(4a^8*7ab) * sqrt(4a^10b^8*2)
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= 2a^4*sqrt(7ab) * 2a^5b^4*sqrt(2)
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= 4a^9b^4*sqrt(14ab)
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Cheers,
Stan H.
</PRE>