Two functions $f(x)$ and $g(x)$ have the property that $$\lim_{x\to\infty}\frac{f(x)}{g(x)}=1$$. What is this referred to as commonly?
All I know of is Big-$\Theta$ notation, which says $$f(x)\in\Theta(g(x))\iff\lim_{x\to\infty}\frac{f(x)}{g(x)}=constant$$, and this could be referred to as "proportional in the limit". But I want to say something even more precise: that the proportionality is by a factor of exactly 1.
Just as an example, $f(x)=2x^3 + 10 x^2$ and $g(x)=2x^3 -5 x$ share this property which I'd like a convenient way to refer to as.