## Elementary Technical Mathematics

$-b(x+6)(x+6)$
This is a perfect square trinomial in the following manner $$-bx^2 -12bx - 36b=-b(x^2+12x+36)=-b(x+6)(x+6) .$$ One can check as follows $$-b(x+6)(x+6)=-b(x^2+12x+36)=-b(x^2+6x+6x+36)=-bx^2 -12bx - 36b .$$