Question

A= (aij) 2^2 tal que aij=(-1) i+j

Answer 1

$A= \left[\begin{array}{ccc}a_{11}&a_{12}\\a_{21}&a_{22}\end{array}\right] \\ \\ A= \left[\begin{array}{ccc}(-1)(1+1)&(-1)(1+2)\\(-1)(2+1)&(-1)(2+2)\end{array}\right] \\ \\ \boxed{A= \left[\begin{array}{ccc}-2&-3\\-3&-4\end{array}\right] }$