Question

giúp mình các câu này với

tìm các giới hạn sau

a/lim\(\)\(\frac{17}{x^2+4}\) (\(x\rightarrow-\infty\))

b/lim\(\frac{-2x^2+x-1}{3+x^2}\) \(x\rightarrow-\infty\)

c/lim\(\frac{x+\sqrt{4x^2-1}}{2-3x}\) (\(x\rightarrow-\infty\))

Answer 1

\(\lim\limits_{x\rightarrow-\infty}\frac{17}{x^2+4}=\frac{17}{+\infty}=0\)

\(\lim\limits_{x\rightarrow-\infty}\frac{-2x^2+x-1}{x^2+3}=\lim\limits_{x\rightarrow-\infty}\frac{-2+\frac{1}{x}-\frac{1}{x^2}}{1+\frac{3}{x^2}}=\frac{-2+0+0}{1+0}=-2\)

\(\lim\limits_{x\rightarrow-\infty}\frac{x+\sqrt{4x^2-1}}{-3x+2}=\lim\limits_{x\rightarrow-\infty}\frac{x-x\sqrt{4-\frac{1}{x^2}}}{x\left(-3+\frac{2}{x}\right)}=\lim\limits_{x\rightarrow-\infty}\frac{1-\sqrt{4-\frac{1}{x^2}}}{-3+\frac{3}{x}}=\frac{1-2}{-3}=\frac{1}{3}\)