Answer
a. $x^2-9$
b. $x^2-25$
Work Step by Step
a. $(x+3)(x-3)$
Use the Distributive Property:
$(x+3)(x-3)=x(x-3)+3(x-3)$
$=x^2-3x+3x-9$
$=x^2-9.$
b. $(x+5)(x-5)$
Use the Distributive Property:
$(x+5)(x-5)=x(x-5)+5(x-5)$
$=x^2-5x+5x-25$
$=x^2-25.$
