$\int\frac{\sqrt{4+x^2}}{x^2}dx$

$\frac{1-cos\left(x\right)}{2sin^2\left(x\right)}$

$13\left(5\right)+13\left(2\right)$

$\int\frac{3\cos\left(5x-1\right)}{4}dx$

$\left(\frac{3x}{x-3}\right)+\left(2\right)=\left(3x-1\right)$

$\lim_{x\to\frac{\pi}{4}}\left(\frac{x}{\left(\sqrt{1+\sin\left(x\right)}\right)-\left(\sqrt{1-\sin\left(x\right)}\right)}\right)$

$9-\left(k+3\right)^2$