$\left(x+1\right)\left(x+3-3x\right)$

$\cos\left(a\right)-\frac{\sin^2\left(a\right)}{\cos\left(a\right)}$

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

$16m^2+48+36$

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

$\frac{5}{x-5}=\frac{x}{x-5}-1$

$\left(x-4\right)dx+\left(y+3\right)dy=0$