$$\lim_{x\to\pi}\left(\frac{\pi-x}{sin\left(2x\right)-1}\right)$$

$$\left(8a+11b\right)\left(8a-11b\right)$$

$$y+x+y+y+x$$

$$6x^{-4}$$

$$3m-6mn-4m-8n$$

$$\left(\frac{1}{2}n+6\right)+\left(\frac{1}{4}n-\frac{1}{2}\right)$$

$$\log_a\left(8\right)=2b-1$$