Question 585188
{{{(4sqrt(5)-8sqrt(2))*(2sqrt(5)+4sqrt(2))}}}
:
FOIL, (when we multiply square roots of like terms we get rid of the radical}
{{{8(5) + 16sqrt(10) - 16sqrt(10) - 32(2)}}}
: 
the middle terms cancel so we have
40 - 64 = -24