The expression above is equivalent to \dfrac{a}{(x+2)^2} (x+2) 2 a start fraction, a, divided by, (, x, plus, 2, ), start superscript, 2, end superscript, end fraction , where aaa is a positive constant and x \neq -2x≠−2x, does not equal, minus, 2. What is the value of aaa?