$\left(x-8\right)\left(x-3\right)$

$\sec\left(t\right)\cdot\cos\left(\frac{t}{2}\right)\:\:-\:\left(\cos\left(t\right)\cdot2sen\left(\frac{t}{2}\right)\right)$

$\int e^{5f+3}df$

$\left(6x^3y^2z+2xy^3\right)^2$

$\int\:\left(\frac{x^3+x^2-3x}{x^2+1}\right)dx$

$x^2-6x=42$

$f\left(x\right)=\left(2-x\right)^2$