$\frac{-12g^3h^6}{20g^8h^{11}}$

$\lim_{t\to0}\left(\frac{\left(1+2t\right)}{t}\right)$

$\lim_{x\to-1}\left(\frac{x^3+2x^2+x}{x^3+x^3+x-1}\right)$

$\lim_{x\to90}\left(\sin\left(\tan\left(\cos\left(x\right)\right)\right)\right)$

$x^4+3x^2=x^2$

$11+-9+20+-3+-12+-1$

$\frac{1}{4x}-\frac{1}{2x^2}=\frac{5}{x^2}$