Cho $f(x)$ và $g(x)$ là các hàm số liên tục trên đoạn $[a;b]$. Mệnh đề nào sau đây đúng?

	$\displaystyle\displaystyle\int\limits_{a}^{b}\big[f(x)-g(x)\big]\mathrm{d}x=-\displaystyle\displaystyle\int\limits_{a}^{b}f(x)\mathrm{d}x-\displaystyle\displaystyle\int\limits_{a}^{b}g(x)\mathrm{d}x$
	$\displaystyle\displaystyle\int\limits_{a}^{b}\big[f(x)-g(x)\big]\mathrm{d}x=-\displaystyle\displaystyle\int\limits_{a}^{b}f(x)\mathrm{d}x+\displaystyle\displaystyle\int\limits_{a}^{b}g(x)\mathrm{d}x$
	$\displaystyle\displaystyle\int\limits_{a}^{b}\big[f(x)-g(x)\big]\mathrm{d}x=\displaystyle\displaystyle\int\limits_{a}^{b}f(x)\mathrm{d}x-\displaystyle\displaystyle\int\limits_{a}^{b}g(x)\mathrm{d}x$
	$\displaystyle\displaystyle\int\limits_{a}^{b}\big[f(x)-g(x)\big]\mathrm{d}x=\displaystyle\displaystyle\int\limits_{a}^{b}f(x)\mathrm{d}x+\displaystyle\displaystyle\int\limits_{a}^{b}g(x)\mathrm{d}x$