Consider the function $\displaystyle {f{{\left({x}\right)}}}={18}{e}^{{-\frac{{x}^{{2}}}{{2}}}}$.

$\displaystyle {f{{\left({x}\right)}}}$ has two inflection points at x = C and x = D with $\displaystyle {C}\leq{D}$
where $\displaystyle {C}$ is Preview Question 6 Part 1 of 5  
and $\displaystyle {D}$ is Preview Question 6 Part 2 of 5  

Finally for each of the following intervals, tell whether $\displaystyle {f{{\left({x}\right)}}}$ is concave up (type in CU) or concave down (type in CD).
$\displaystyle {\left(-\infty,{C}\right]}$:
$\displaystyle {\left[{C},{D}\right]}$:
$\displaystyle {\left[{D},\infty\right)}$