Please provide Regular Expression's for all three?

Question

Comments

Please provide step by step way

Answer 1

1. (a+b)* (aⁿbⁿ) n>=0

2. a*(aⁿ⁺¹bⁿ) with null.

3. (aⁿ⁺¹ bⁿ)[with null]  a (a+b)*

Comments

Yes,  i get this one. Please add diagram it was better. I still have some doubt.

For 3rd it should be $a^*(a+b)^*$

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in 3^rd B  -> aⁿbⁿ .n>=0.

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Yes i agree $B = (a^nb^n)$ and $A = a^*$. So what should be $S$??