$-3a^2b+8ab^2-b^3$

$2\left(5-b\right)-2\left(b+5\right)$

$21xy+63+9y+27$

$\left(\sqrt[3]{27}\right)^{-6n}\cdot3^2\cdot3^3$

$\frac{2}{5}a-\frac{4}{3}a+\frac{1}{2}a$

$\int\frac{cos\left(x\right)\cdot sen\left(x\right)}{1-cos\left(x\right)}dx$

$\frac{dy}{dx}\:=\left(\frac{2y^4}{x^5}\right)\:$