Lim (x-кореньx^2 x—>беск. +7х+10)= Помогите плиз!!!!!!!

Решите задачу:

$\displaystyle \lim_{x \to \infty} (x-\sqrt{x^2+7x+10})=\\\\\\=\lim_{x \to \infty} \frac{(x-\sqrt{x^2+7x+10})(x+\sqrt{x^2+7x+10})}{x+\sqrt{x^2+7x+10}}=\\\\\\=\lim_{x \to \infty} \frac{x^2-(x^2+7x+10)}{x+\sqrt{x^2+7x+10}}=\lim_{x \to \infty} \frac{-7x-10}{x+\sqrt{x^2+7x+10}}=\\\\\\=\lim_{x \to \infty} \frac{-\frac{7x}x-\frac{10}x}{\frac{x}x+\sqrt{\frac{x^2}{x^2}+\frac{7x}{x^2}+\frac{10}{x^2}}}=\frac{-7-0}{1+\sqrt{1+0+0}}=-\frac{7}{1+1}=-\frac{7}2$