How prove this matrix inequality $\det(B)>0$ Let $A=(a_{ij})_{n\times n}$ such
$a_{ij}>0$ and $\det(A)>0$.
Defining the matrix $B:=(a_{ij}^{\frac{1}{n}})$, show that $\det(B)>0?$.
This problem is from my friend, and I have considered sometimes, but I can't. Thank you 

The statement is false. Counterexample:
$$
B=\pmatrix{2&2&2\\ 3&4&2\\ 3&1&4},\ A=B\circ B\circ B=\pmatrix{8&8&8\\ 27&64&8\\ 27&1&64},\ \det(B)=-2,\ \det(A)=7000.
$$
Edit. However, if $B$ is positive definite, the converse of your statement is true. More specifically, suppose $B$ is positive definite (whether it is entrywise positive is unimportant) and $A$ is the $n$-fold Hadamard product of $B$ (i.e. $A=(b_{ij}^n)$). Then $\det(A)>0$. This is because for positive semidefinite matrices $X$ and $Y$, we have $\det(X\circ Y)\ge\det(X)\det(Y)$.
