$\lim_{x\to-\infty}\left(\frac{3x+1}{3x+4}\right)^{\left(\frac{2x^2+1}{x-3}\right)}$

$\frac{16-x^{16}}{2-x^4}$

$\frac{2}{7}=\frac{b+1}{56}$

$\int\frac{x+19}{x^2-2x-15}dx$

$\frac{4x^5}{x^3}+\left(-3x^2\right)$

$x=3\tan\left(y\right)$

$\int\sin\left(6x\right)\cos\left(4x\right)dx$