$27x\:+x^2$

$\int\frac{1}{x\left(3+in\text{\x}\ \right)}dx$

$f\left(x\right)=\frac{1}{\left(x^6-6x\right)^3}$

$x^2-1.8x+0.81$

$28-2m;\:m=7$

$\left(m-13\left(m+13\right)\right)$

$\left(e^{\left(x\right)}\right)\left(y\right)\left(y'\right)=\left(e^{\left(-y\right)}\right)+\left(e^{\left(-2x-y\right)}\right)$