#### Answer

$\dfrac{1}{x+3}-\dfrac{1}{(x+3)^{2}}=\dfrac{x+2}{(x+3)^{2}}$

#### Work Step by Step

$\dfrac{1}{x+3}-\dfrac{1}{(x+3)^{2}}$
Evaluate the substraction of the two rational expressions:
$\dfrac{1}{x+3}-\dfrac{1}{(x+3)^{2}}=\dfrac{(x+3)^{2}-(x+3)}{(x+3)^{3}}=...$
Take out common factor $x+3$ from the numerator and simplify:
$...=\dfrac{(x+3)[(x+3)-1]}{(x+3)^{3}}=\dfrac{x+3-1}{(x+3)^{2}}=\dfrac{x+2}{(x+3)^{2}}$