Final answer:
The other factor of the expression ab + bc when factoring out b is (a + c).
Step-by-step explanation:
When we are given that b is a factor of the expression ab + bc, we can factor out b to find the other factor. The process involves examining each term in the expression and identifying the common factor. Since both terms contain b, we factored b out, which leads us to the expression b(a + c). In this case, the other factor alongside b is (a + c).
To illustrate, we can take an expression such as 3b + 3c. Here, the common factor is 3, and the expression can be factored as 3(b + c). Looking back at our original problem, if b is the known factor, the other factor, as we have determined, is (a + c).