$\frac{dy}{dx}=-6x-30$

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

$\pi.r^2;\:r=10;r=100$

$2\pi+7-8\sqrt{2}+5\pi-3\sqrt{2}$

$\left(6+5a\right)^2\left(6-5a\right)^2$

$\left(\frac{5^{-4}\cdot5^{-1}}{3^2\cdot5^{-3}}\right)^{-\frac{1}{2}\left(\frac{3^4\cdot5^3}{3^2\cdot5^4}\right)^{-1}}$

$\left(a^2-b^2-c^2+2abc\right)\left(a+b-c\right)$