$$x\left(\tan\left(47\right)-\tan\left(17\right)\right)=389\:\tan\left(17\right)$$

$$9^7\cdot9^{-5}$$

$$\frac{80}{2}$$

$$\frac{x^2-5x+33}{x+5}$$

$$\frac{5sin\left(x\right)sec\left(x\right)}{tan\left(x\right)}$$

$$tan^4x+tan^2x=sec^4x-sec^2x$$

$$9x^2+5x+2\:\:para\:x=-1$$