Precalculus: Mathematics for Calculus, 7th Edition

$(A + B)^2$ $(x + 5)^2$
The Special Factoring Formula for a "perfect square" is the opposite of the Special Product Formula for a "perfect square", which is: $(A + B)^2$ = $A^2$ + 2AB + $B^2$ therefore, the Special Factoring Formula is: $A^2$ + 2AB + $B^2$ = $(A + B)^2$ For the trinomial $x^2$ + 10x + 25, $A^2$ = $x^2$ and $B^2$ = 25, so A = x and B = 5. Therefore, this trinomial factors as: $(x + 5)^2$