A graph of $f$ is shown above. The numbers shown represent the geometric area of each region. Evaluate the following definite integrals.

1. $\displaystyle{ \int_0^{1} f(x) \, dx }$ =
2. $\displaystyle{ \int_{0}^{2} f(x) \, dx }$ =
3. $\displaystyle{ \int_0^{3} f(x) \, dx }$ =
4. $\displaystyle{ \int_{1}^{2} -6 f(x) \, dx }$ =