Answer
$-8\sqrt 5$
Work Step by Step
$(\sqrt 5-5)(2\sqrt 5+2)$
=$\sqrt 5(2\sqrt 5+2)-5(2\sqrt 5+2)$
=$2\sqrt 5\sqrt 5+2\sqrt 5-10\sqrt 5-10$
=$2(5)+2\sqrt 5-10\sqrt 5-10$
=$10+2\sqrt 5-10\sqrt 5-10$
=$10-10+(2-10)\sqrt 5$
=$-8\sqrt 5$
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