1, [tex]\lim_{x\to -\infty}(\sqrt{x^{2}+x}-x)=\lim_{x\to -\infty}\frac{x^{2}+x-x^{2}}{\sqrt{x^{2}+x}+x}=\lim_{x\to -\infty}\frac{x}{\sqrt{x^{2}+x}+x}=\lim_{x\to -\infty}\frac{1}{-\sqrt{1+\frac{1}{x}}+1}=+\infty[/tex]
(do x âm nên [tex]1+\sqrt{1}{x}<1=>-\sqrt{1+\frac{1}{x}}+1>0[/tex])
2, [tex]x \to 3^{+}=> 3-x \to 0^{-}; 2x \to 6=> \lim_{x\to3^{+}}\frac{2x}{3-x}=-\infty[/tex]
3, [tex]\lim_{x\to1}\frac{5}{(x-1)(x^{2}-3x+2)}=\lim_{x\to1}\frac{5}{(x-1)^{2}(x-2)}[/tex]
[tex]x\to1=>x-2\to-1;(x-1)^{2}\to0^{+}=>\lim_{x\to1}\frac{5}{(x-1)^{2}(x-2)}=-\infty[/tex]
[TẶNG BẠN] TRỌN BỘ Bí kíp học tốt 08 môn
