irresolvable vs unsolvable

irresolvable

adj

  • Impossible to resolve; insoluble. 

  • Impossible to separate into its component parts. 

unsolvable

adj

  • Not solvable. 

noun

  • A problem that cannot be solved. 

How often have the words irresolvable and unsolvable occurred in a corpus of books? (source: Google Ngram Viewer )