If $\frac{2x + 6} {(x + 2)^2}- \frac{2} {x + 2} = \frac{a} {(x + 2)^2}$, then what is $a$? $$\frac{2x + 6} {(x + 2)^2}- \frac{2} {x + 2}$$
The expression above is equivalent to $$\frac{a} {(x + 2)^2}$$
where $a$ is a positive constant and $x \neq -2$.
What's the value of $a$?

We have
$$2x+\frac{6}{(x+2)^2}-\frac{2}{x+2}=\frac{a}{(x+2)^2}$$
$$2x(x+2)^2+6-2(x+2)=a$$
$$2x^3+4x^2+4x+6-2x-2=a$$
$$2x^3+4x^2+2x+4=a$$
