Question 195954
(5sqrt2 +2sqrt3) ( sqrt2 -2sqrt3)
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use  F O I L
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5 sqrt2 sqrt2 - 5*2 sqrt2 sqrt3 +2sqrt3 sqrt2 -2*2sqrt3 sqrt3
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5*2 -10 sqrt6 +2 sqrt6 -4 *3
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10 -8sqrt6 -12
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-2 -8 sqrt6
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checking
using  calculator,,original  =  -21.6,,,answer  = -21.6,,,,ok