$$\lim_{h\rightarrow0}\ \frac{f\left(x_0+h\right)-f\left(x_0\right)}{h}$$

$$\lim_{h\rightarrow0}\ \frac{f\left(x_0-h\right)-f\left(x_0\right)}{h}$$

$$\lim_{h\rightarrow1}\ \frac{f\left(x_0+h\right)-f\left(x_0\right)}{h}$$

$$\frac{Dg\left(x\right)\cdot f\left(x\right)-g\left(x\right)\cdot Df\left(x\right)}{g^2\left(x\right)}$$

$$\frac{Df\left(x\right)\cdot g\left(x\right)-f\left(x\right)\cdot Dg\left(x\right)}{g^2\left(x\right)}$$

$$\frac{Df\left(x\right)\cdot g\left(x\right)-f\left(x\right)\cdot Dg\left(x\right)}{g\left(x\right)}$$