What kind of model relies on direct observation, measurement, and extensive data? an empirical model a mechanistic model a foundational model an optimization model

In a word processing program, such as microsoft word, which feature to you choose the desired picture enhancement?

You wanted to look up information about alzheimer's, but you were unsure if it was spelled "alsheimer's" or "alzheimer's." which advanced search strategy would be useful? a) a boolean search b) using a wild card in your search c) trying different search engines d) doing a search for "alsheimer's not alzheimer's" asap. ill give brainlist.

Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < b < 10 using this index, in terms of the number of records n2 that satisfy this selection, as well as n1 and h defined above? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?