Срочняк нода помогите

Решите задачу:

$1. \lim_{x \to \infty} \frac{x^2(3 + \frac{1}{x}- \frac{6}{x^2}) }{x^2(7 + \frac{1}{x^2})} = \lim_{x \to \infty} \frac{3 + \frac{1}{x}- \frac{6}{x^2}}{7 + \frac{1}{x^2}} = \frac{3}{7} \\\\ 2. \lim_{x \to 0} \frac{ \sqrt{x+4}-2 }{x} =\lim_{x \to 0} \frac{ (\sqrt{x+4}-2)(\sqrt{x+4}+2) }{x(\sqrt{x+4}+2)} =\lim_{x \to 0} \frac{ x+4-4}{4x}=\\=\lim_{x \to 0} \frac{ x}{4x}= \frac{1}{4}$
$3. \lim_{x \to 0} \frac{tg^2x}{x*sin3x} = \lim_{x \to 0} \frac{x^2}{x*3x} = \lim_{x \to 0} \frac{x^2}{3x^2} = \frac{1}{3} \\\\ 4. \lim_{x \to 1} \frac{(x-1)(3x+1)}{(x-1)(x+1)} =\lim_{x \to 1} \frac{3x+1}{x+1}= \frac{4}{2} =2$