Limites
Enviado: Qua 05 Abr, 2017 14:24
Calcule o limite abaixo:
[tex3]\lim_{x \rightarrow \infty}x-\sqrt{x^{2}+3x}[/tex3]
[tex3]\lim_{x \rightarrow \infty}x-\sqrt{x^{2}+3x}[/tex3]
[tex3]x-\sqrt{x^2+3x}=[/tex3]
[tex3]=(x-\sqrt{x^2+3x})\left(\frac{x+\sqrt{x^2+3x}}{x+\sqrt{x^2+3x}}\right)[/tex3]
[tex3]=\frac{x^2-\mid x^2+3x\mid}{x+\sqrt{x^2+3x}}[/tex3]
[tex3]=\frac{3x}{x+\sqrt{x^2+3x}}[/tex3]
[tex3]=\frac{1}{\frac{x+\sqrt{x^2+3x}}{3x}}[/tex3]
[tex3]=\frac{1}{\frac{x}{3x}+\sqrt{\frac{x^2+3x}{9x^2}}}[/tex3]
[tex3]=\frac{1}{\frac{1}{3}+\sqrt{\frac{1}{9}+3x^{-1}}}[/tex3]
Assim,
[tex3]\lim_{x\rightarrow\infty}x-\sqrt{x^2+3x}=\lim_{x\rightarrow\infty}\frac{1}{\frac{1}{3}+\sqrt{\frac{1}{9}+3x^{-1}}}=\frac{1}{\frac{1}{3}+\sqrt{\frac{1}{9}+\lim_{x\rightarrow\infty}3x^{-1}}}=\frac{1}{\frac{1}{3}+\sqrt{\frac{1}{9}+0}}=\frac{1}{2}[/tex3]