Final answer:
To simplify the given expression of root 45 - 3 root 20 + 4 root 5, combine the like terms to get root 5.
Step-by-step explanation:
To simplify the given expression:
Root 45 = 3 * root 5
-3 * Root 20 = -3 * 2 * root 5 = -6 * root 5
4 * Root 5 = 4 * root 5
Now, we can combine similar terms to get:
(3 - 6 + 4) * root 5 = 1 * root 5 = root 5