Алгебра, помогите ...............................

Решите задачу:

$f(x)=\frac{2x^3+1}{10x^3-3x^2-7x+2}\\\\\lim\limits _{x\to -\infty }f(x)=\lim\limits _{x \to -\infty} \frac{2x^3+1}{10x^3-3x^2-7x+2}= \lim\limits _{x \to -\infty} \frac{2+\frac{1}{x^3}}{10-\frac{3}{x}-\frac{7}{x^2}+\frac{2}{x^3}} =\frac{2}{10}=\frac{1}{5}\; \Rightarrow \\\\y=\frac{1}{5}\; \; -\; \; gorizontalnaya\; \; asimptota\\\\b=\frac{1}{5}$