Answer:
-2sqrt5
Step-by-step explanation:
Lets begin by simplifying the radicals.
20 can be factored into 4*5, and since 4 is a perfect square, we can take out a 2.
therefore:
sqrt20 = 2sqrt5
80 can be factored into 16*5, and since 16 is a perfect square, we can take out a 4
therefore:
sqrt80 = 4sqrt5
So finally we have, 2sqrt5-4sqrt5 = -2sqrt5
