$alpha_{x\to0}\left(\frac{7x^2}{cosx-1}\right)$

$5x\left(x^4\right)^2$

$x^2+8x-3=0$

$-4x+7=15$

$-\left|13+\left(-4\right)\right|-\left(-12\right)-2+4-\left(-1\right)$

$\lim_{x\to39}\left(\frac{cos\left(xt\right)-\cos\left(39t\right)}{1521-x^2}\right)$

$\sqrt{\frac{x^{14}}{x^2}}$