$\frac{\cot^{2}x-1}{\cot^{2}x+1}=2\cos^{2}x-1$

$\frac{d}{dx}\sqrt{18x}$

$\left(\sec\left(a\right)-1\right)\left(\sec\left(a\right)+1\right)$

$\int\left(\frac{3}{x^2\sqrt{1+x^2}}\right)dx$

$\left(3+3+3+3+3+3+3+3+3+3+3\right).\left(-2\right).\left(-5\right)$

$y'=x^8$

$x^2-7x-3$