Peter Linz Edition 5 Exercise 11.2 Question 4 (Page No. 290)

Question

Prove that constructed grammar cannot generate any sentence with $a\space b$ in it.

                                                                             $S\rightarrow S_1B,$

                                                                           $S_1\rightarrow aS_1b,$

                                                                           $bB\rightarrow bbbB,$

                                                                           $aS_1b\rightarrow aa,$

                                                                               $B\rightarrow \lambda$