SOLUTION: can not figure out how to come to the answer to this problem... (4√5-8√2)*(2√5+4√2)please help

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Question 585188: can not figure out how to come to the answer to this problem...
(4√5-8√2)*(2√5+4√2)please help
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
%284sqrt%285%29-8sqrt%282%29%29%2A%282sqrt%285%29%2B4sqrt%282%29%29
:
FOIL, (when we multiply square roots of like terms we get rid of the radical}
8%285%29+%2B+16sqrt%2810%29+-+16sqrt%2810%29+-+32%282%29
:
the middle terms cancel so we have
40 - 64 = -24