$-\:9t^2+5t-4t$

$\left(\frac{\frac{21}{17}+3}{4}\right)+\left(\frac{\frac{21}{17}+6}{3}\right)=\left(2\left(\frac{21}{17}\right)+1\right)$

$\int\frac{x}{\left(5+x^2\right)^6}dx$

$\frac{csc^2\left(\theta\right)-1}{1+cot^2\left(\theta\right)}$

$\frac{d}{dx}\sqrt{\frac{x^2-9}{x}}$

$a^6-b^4$

$\frac{2}{3}x<4$