$\lim_{x\to\infty}\left(\frac{8x^2}{cos\left(x\right)-1}\right)$

$\int\sqrt{9x+28}dx$

$\cos\left(x\right)-\cos\left(2x\right)=1$

$5x\:.\:y\:=\:5xy$

$\int_0^{\frac{\pi}{4}}\left(22\sec^4\left(x\right)\right)dx$

$w^4.w^2.w$

$\lim_{x\to0}\left(\frac{3+x}{x\left(x-8\right)}\right)$