$2\cdot\left(-\left(-3\right)\cdot2+1\right)\cdot5$

$\lim_{\theta\to\frac{\pi}{4}\frac{\cos\left(2\theta\right)}{\sqrt{2}\cos\left(\theta\right)-1}}$

$\frac{1}{\cos\left(x\right)}-\frac{\cos\left(x\right)}{1+\sin\left(x\right)}=\tan\left(x\right)g$

$4x-4=40$

$\left(z^7-3\right)\cdot\left(z^7+3\right)$

$-5x+13y=-7$

$4x^3-5x^2$