$\int\frac{x^2}{\left(7-x^3\right)^2}dx$

$\lim_{h\to9}\left(\frac{h^2-h-72}{h-9}\right)$

$-72\:\:.\:\:\left(-5\right)$

$\frac{3}{2x-9},\:c=6$

$\left(\frac{2}{3}a^3+\frac{1}{2}a\right)\left(\frac{2}{3}a^3-\frac{1}{2}a\right)$

$\left(4p-s\right)\left(4p+s\right)$

$\csc\theta\left(1-\cos^{2}\theta\right)=\sen\theta$