Asymptotic Notation in Equations

Example: 2n² + 3n + 1 = 2n² + $\Theta(n)$

In other words, there is some function f(n) element of $\Theta(n)$that makes the equation true; namely, 3n + 1.

2n² + 3n + 1 = 2n² + $\Theta(n)$ = $\Theta(n^2)$.

In other words, for any function f(n) element of $\Theta(n)$, there is some function h(n) element of $\Theta(n^2)$; namely, 2n² + f(n).