Answer:
-1 or -4
Step-by-step explanation:
first all you have to do is to multiply 12 by 3b² to give you 36b² and then find a number(x) multiplied by another number(y) to give you 36b² and those two numbers must sum up to give you 15b
doing this, we would have our two numbers to be
12b and 3b
replace these two numbers with 15b in the equation
3b² + 12b + 3b + 12=0
(3b²+12b) + (3b+12)=0
3b(b+4)+3(b+4)=0
note: the numbers in the brackets must be the same
(3b+3)(b+4)=0
therefore, 3b + 3= 0 or b + 4= 0
3b+3= 0
3b=-3
b=-3/3
b=-1
or
b+4=0
b=-4
