$$\frac{4+x}{16+8x+x^2}$$

$$\left(5x+3\right)-\left(8x-2\right)$$

$$\lim_{x\to0}\left(\frac{sin\left(x^7\right)}{x}\right)$$

$$\left(-6\right)\cdot5+\left(-6\right)\cdot\left(-1\right)$$

$$2+6+7$$

$$15\cos^2x-17\cos x+4=0$$

$$\int-6xe^{2x}dx$$