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

$\left|+5\left(-4\right)\cdot\left(-6\right)\right|$

$x^2\:+\:26x\:+\:25$

$\left(x\right)\left(\sqrt{\frac{x}{y}}\right)-\left(y\right)\left(\frac{\left(\frac{x}{y}\right)^{\frac{3}{2}}}{3}\right)$

$8y^2+40y+50$

$\lim_{x\to\infty}\left(\left(1+\frac{3}{x^3}\right)^{2lnx}\right)$

$3\cdot y-6\cdot z+9^2$