Giải thích các bước giải:
Câu 20:
$\lim_{x\to 1}\dfrac{\sqrt[3]{2x-1}-1}{x-1}$
$=\lim_{x\to 1}\dfrac{2x-1-1}{(x-1)(\sqrt[3]{(2x-1)^2}+\sqrt[3]{2x-1}+1)}$
$=\lim_{x\to 1}\dfrac{2(x-1)}{(x-1)(\sqrt[3]{(2x-1)^2}+\sqrt[3]{2x-1}+1)}$
$=\lim_{x\to 1}\dfrac{2}{\sqrt[3]{(2x-1)^2}+\sqrt[3]{2x-1}+1}$
$=\lim_{x\to 1}\dfrac{2}{\sqrt[3]{(2.1-1)^2}+\sqrt[3]{2.1-1}+1}$
$=\dfrac{2}{3}$