grandes-ecoles 2023 Q10

grandes-ecoles · France · mines-ponts-maths1__psi Proof Direct Proof of an Inequality
Show the inequality
$$\forall ( A , B ) \in S _ { n } ^ { + + } ( \mathrm { R } ) ^ { 2 } , \quad \operatorname { det } ^ { 1 / n } ( A + B ) \geq \operatorname { det } ^ { 1 / n } ( A ) + \operatorname { det } ^ { 1 / n } ( B )$$
Show the inequality

$$\forall ( A , B ) \in S _ { n } ^ { + + } ( \mathrm { R } ) ^ { 2 } , \quad \operatorname { det } ^ { 1 / n } ( A + B ) \geq \operatorname { det } ^ { 1 / n } ( A ) + \operatorname { det } ^ { 1 / n } ( B )$$