$2k^2+4k+1$

$f\left(x\right)=x^2+2x-15$

$\frac{d}{dx}\left(3x^2y-4xy+x-2y=6\right)$

$5\:.\:11^{-8}\:.\:11^7$

$\sqrt[3]{53x^2y^4}$

$\frac{\cos\left(x-y\right)-\cos\left(x\right)\cdot\cos\left(y\right)}{\cos\left(x\right)\cdot\sin\left(y\right)}$

$\int\frac{\sqrt{1-\sqrt{t}}}{\sqrt{t}}dt$