Determine the points of inflection in each graph.
Can someone check my answers below for correctness? Thanks in advance.
therefore no poitns of inflection
b) f(x)= e^x + e^(-x)
f''(x)= 0 DNE
therefore no points of inflection
c) f(x)= x-lnx
f''(x)=undefined when x=0
therefore point of inflection is (0,0)
d) f(x)=x^4 + 4x^3
f''(x)=0 when x= -2 or x=0
therefore points of inflection are (0,0) and (-2,-16)
let me know which ones are wrong and the correct method to answering the question.