$\frac{20k^4}{12k^3}$

$\lim_{x\to0}\left(\frac{\ln\left(x^2+3x\right)}{\ln\left(x\right)}\right)$

$x-5\sin3x^2$

$\int\left(\frac{1}{tg\left(v\right)}\right)dv$

$\int_0^{12}\left(-\frac{5}{12}x^3+64.7x-187.0\right)\left(\frac{1}{3}x-\left(x-8\right)\right)dx$

$\int\left(sin\left(x+8\right)\right)dx$

$100b^2-81c^2$