Question

tính

a) \(\lim\limits_{x\rightarrow3^-}\dfrac{-4x}{x-3}\)

b)  \(\lim\limits_{x\rightarrow3^+}\dfrac{-4x}{x-3}\)

Answer 1

a: \(\lim\limits_{x\rightarrow3^-}\dfrac{-4x}{x-3}\)

\(\lim\limits_{x\rightarrow3^-}x-3=3-3=0\)

\(\lim\limits_{x\rightarrow3^-}-4x=-4\cdot3=-12< 0\)

=>\(\lim\limits_{x\rightarrow3^-}-\dfrac{4x}{x-3}=-\infty\)

b: \(\lim\limits_{x\rightarrow3^+}\dfrac{-4x}{x-3}\)

\(\lim\limits_{x\rightarrow3^+}x-3=3-3=0\)

\(\lim\limits_{x\rightarrow3^+}-4x=-4\cdot3=-12< 0\)

=>\(\lim\limits_{x\rightarrow3^+}\dfrac{-4x}{x-3}=-\infty\)