Determine the regions of concavity?
y is concave DOWN when: *slope, aka y ’ is decreasing, and/or *when y ‘’ < 0.
y is concave UP when: * y ’ (aka slope of y) is increasing, and/or when y ‘’ > 0.
You can technically use y ’ to figure it out, but it’s easy to make mistakes this way for some reason. It’s best to always use y ‘’ for concavity.