For determining intervals, you always have to look at the x axis. It always goes from left to right. So you have to look where it is increasing from left to right, and where it is decreasing from left to right.
increasing: [-2,0] , [2,4]
Decreasing: [-4,-2] , [0, 2] , [4, 6]
Feb 15th, 2015
Did you know? You can earn $20 for every friend you invite to Studypool!