## Introductory Algebra for College Students (7th Edition)

$(A-B)^2$
RECALL: A perfect square trinomial can be factored using either of the following formulas: (i) $a^2+2ab+b^2 = (a+b)^2$ (ii) $a^2-2ab+b^2=(a-b)^2$ The given perfect trinomial is of the same form as the one in formula (ii) above. Thus, the missing expression in the given statement is: $(A-B)^2$