Lim (1+5x)^3+x/x^2
x-0

[tex] \lim\limits _{x \to 0}\frac{(1+5x)^3+x}{x^2}=\Big [\, \frac{(1+0)^3+0}{0^2}=\frac{1}{0}\, \Big ]=\infty [/tex]