so to find when a graph is concave up or down you can use the 2nd derivative rule, but what happends if we have f"(x) = -3(x^2 +3)/(X^2-9)^3(adsbygoogle = window.adsbygoogle || []).push({});

what im thinking is that we are looking for f"(x)=0 so x^2+3= O but that would give us x=(-3)^1/2...

any thoughts?

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# 2nd derivative rule

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