$-9x^5-12x^4+2x^2+x+2$

$x^2=72$

$28-2m,\:con\:m=7$

$\lim_{x\to\infty}\left(1+\frac{28}{x}\right)^x$

$\int2x^4\cdot\arccot\left(2x\right)dx$

$\lim\:_{t\to\:0}\left(\frac{t^2}{\sin\:\:^2\left(t\right)}\right)$

$\int_1^{\infty}\left(\frac{x}{\left(bx^2+1\right)^3}\right)dx$