$\tan\left(a-b\right)=\frac{\cot\left(b\right)-\cot\left(a\right)}{\cot\left(a\right)\cot\left(b\right)+1}$

$\left(2\ln\left(2x+y+3\right)-1\right)dx+\ln\left(2x+y+3\right)dy=0$

$f\left(x\right)=\frac{2x-4}{\sqrt{x^2-4}}$

$-5\:\cdot\:-56$

$5^3+3\left(3\right)^2+3\left(3\right)+1$

$4x^2\left(x^3+5\right)^9$