Step-by-step explanation:
[tex]36 - {b}^{2} - {c}^{2} + 2bc[/tex]
Factor out -1
[tex] - ( - 36 + {b}^{2} + {c}^{2} - 2bc[/tex]
[tex] -( (b + c) { }^{2} - 36[/tex]
[tex] - (b + c + 6)( b + c - 6)[/tex]
