$8x^2+9x+1$

$\lim_{x\to\infty}\left(\frac{x-3}{\cos\left(x\right)+x}\right).$

$\frac{1}{\cos\left(x\right)^2}+\tan\left(x\right)^2=2$

$5\cdot5\cdot5\cdot6\cdot6$

$\frac{dy}{dx}=\frac{y}{x}+cos\left(\frac{y-x}{x}\right)$

$\sin\left(a\right)=\frac{\sin\left(x\right)+\tan\left(x\right)}{1+\sec\left(x\right)}$

$\left(2y\right)dx=\left(5y+2x\right)dy$