$\left(1-\csc a\right)^2$

$\left(\frac{1}{4}x^4\frac{5}{2}x^3+1\right)+\left(\frac{1}{7}x^2+\frac{3}{2}x-\frac{3}{4}\right)+\left(\frac{2}{3}x^4+3x^3-2x^2-\frac{1}{5}\right)$

$\lim_{x\to0}\left(\frac{\sqrt{5+x}-\sqrt{6}}{x}\right)$

$x+2-\left(-2x\right)=x+5-\left(x-3\right)$

$\frac{x^2x^4x^{-2}}{x^{-2}}$

$\frac{1}{\sin\left(-x\right)^2}=\csc$

$\left(\sqrt{5}\:y-3z\right)^2$