$cos\left(-\frac{1}{7}\right)cos\left(-\frac{1}{4}\right)-sin\left(-\frac{1}{7}\right)sin\left(-\frac{1}{4}\right)$

$ln\left(x\right)-ln\left(x+2\right)=ln\left(6\right)$

$\int\frac{2}{v}dv$

$x^2+21-4x$

$\lim\:_{x\to\:\:\infty\:}\left(\frac{\left(x^3\right)}{\left(e^{2x}\right)}\right)$

$\left(mn^2-4\right)\left(mn^2+4\right)$

$a^2-3a+6$