Instructions: Solve only $10$ problems.

Non Regular Language $(10\%)$

Use the Pumping Lemma to show that the following language over $\{a,b\}$ are not regular

$L=\{x|n_a(x)=n_b(x)\}$

Non Regular Language $(10\%)$

Use the Pumping Lemma to show that the following language over $\{a,b\}$ are not regular

$L=\{{?}^R|xin\{a,b{\}}^{**}\}$