How do you find the critical numbers of #f(x)=|x+3|-1#?
x=c is a Critical Point either where (A) f'(c) = 0 or (B) f('c) does not exist/ is not defined
if you look at the 2 versions of this you have
and for when
the lines meet at
Point (-3,-1) is an apex. The derivative immediately to the left and right are -1 and 1 respectively. but the derivative at the point (-3,-1) is not defined. that is the CP here.
plot it if in doubt