$[15]5)$ Find any local min or max: $f(x)=x^3-2x$

$10,f^{\text{'}}(x)=3x^2-2$

$[15]6)$ where is the graph concave up or down: $f(x)=x^3-2x$

$f(x)=x^3-2x$;$f^{\text{'}}(x)=f^{\text{'}\text{'}}(x)=-2<mn>0</mn>$ forall

$x=fisis$ for all XER

$f^{\text{'}\text{'}}(x)=6x$