$1a\:-\:5$

$\frac{1}{2}\left(\cos\left(a-b\right)-\cos\left(a+b\right)\right)$

$\left(x+5\right)x\le2\left(x^2+2\right)$

$\left(\frac{x^2+x-6}{x^2-9}\right)$

$\int\frac{5}{\left(3x+6\right)^4}dx$

$\left(x-6\right)^2\left(x^2-12x+36\right)$

$sin^2\theta\:+tan^2\theta\:+cos^2\theta\:$