$$a^{6}-b^{8}$$

$$\lim_{x\to\infty}\frac{2^x}{3^{x-1}}$$

$$-15-\left(-6\right)+\left(-7\right)-\left(3\right)$$

$$x^2-\frac{2}{5}x+\frac{4}{25}=-1+\frac{4}{25}$$

$$\lim_{x\to0}\frac{2-2\cos\left(x\right)}{\sin\left(4x\right)}$$

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

$$14\cdot14\cdot4$$