Answer:
[tex]\text{Solution:}\\\\1.\ \text{When slowing down, acceleration will be negative.}\\\therefore\ 12t-6 < 0\\\text{or, }12t < 6\\\text{or, }t < 1/2\\\text{So acceleration will be negative for all }t < 1/2.\\\therefore\ t \in(-\infty,1/2)[/tex]
[tex]\text{2. When speeding up, the acceleration will be positive.}\\\therefore\ 12t-6 > 0\\\text{or, }12t > 6\\\text{or, }t > 1/2\\\text{So the acceleration function will be positive for all }t > 1/2.\\\therefore\ t\in (1/2,\infty)[/tex]
