Is the absolute value of a strictly convex function also convex?

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If $f(x)^2$ is strictly convex, then is $|f(x)|$ convex or not?

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No. If $f:\mathbb R\to\mathbb R$ is $f(x)=|x|^{2/3}$ then $f^2(x)=|x|^{4/3}$ is strictly convex, but $|f(x)|=|x|^{2/3}$ is not.