# Regular Expression Kleene Star application - using 0s and 1s

Have a question from an online course I am trying to take for a certificate. Came across a few questions like this and need help working through the problem and the rationale to get the solution. Any help appreciated.

Consider the regular expressions R1 = (01)*(0*1*)(10) and R2 = (101)(01). Which of following is true?

10 in R1 and 101 R2

10 in R1 and 1000 R2

010 in R1 and 100 R2

010 not in R1 and 100 not in R2

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• What did you try? Where did you get stuck? We're happy to help you understand the concepts but just solving exercises for you is unlikely to achieve that. You might find this page helpful in improving your question. We're not looking for questions that are just the statement of an exercise-style task and a request for someone to solve it for you. If you understood the concepts, these should be straightforward, so I suggest trying to figure out what about the concepts you don't understand yet. – D.W. 2 days ago