Tìm giới hạn của $T=\mathop {\lim }\limits_{x \to 0} \frac{2\sqrt{1+x}-\sqrt[3]{8-x}}{x}$$A=\mathop {\lim }\limits_{x \to 1} \frac{\sqrt[4]{2x-1} + \sqrt[5]{x-2} } {x-1}$$B=\mathop {\lim }\limits_{x \to 0} \frac{1-\cos x\cos 2x}{x^2}$$C=\mathop {\lim }\limits_{x \to 0} \frac{\sin (\sin x)}{x}$