$$x^2+2y^2=13k^2$$

$$\left(secx\right)\left(\frac{cotx}{sinx}\right)=csc^2x$$

$$sen^2sec^2+sen^2csc^2=sec^2$$

$$\left(\frac{4xy}{y^3}\right)^{-3}$$

$$7x-3\ge10$$

$$\log\:\frac{x^3y^2}{\sqrt{z^5}}$$

$$-\left(7\:-\:4\right)\:-\:14\:$$