find concave up and down
The Attempt at a Solution
I found the second derivative to b
i found the only inflection point was x=0 (which was correct)
I plugged in values on both the right and left side of 0 and determined that f(x) was concave down on all values smaller than 0 with the exception of -5, and f(x) was concave up on all values larger than 0 with the exception of 5
however this is not the correct answer. Can someone confirm/tell me what i am doing wrong?