Invest is etymologically related to Investigate. Investigate is a type of Analyze. Diagnose is a type of Analyze. 
Expensive is a synonym of Costly. Costly is related to Dear. Dear is related to Introduction. Introduction is derived from Introduce. 
Invest --EtymologicallyRelatedTo--> Investigate --IsA--> Analyze <--IsA-- Diagnose 
Expensive <--Synonym--> Costly <--RelatedTo--> Dear <--RelatedTo--> Introduction --DerivedFrom--> Introduce 