Question

determine x para que o determinante da matriz ...... (mandei foto) seja igual a zero.​

Answer 1

$\boxed{\begin{array}{l}\rm Determine~x~para~que~o~determinante~seja~nulo.\\\begin{vmatrix}\sf1+x&\sf-1\\\sf3&\sf1-x\end{vmatrix}\\\underline{\rm soluc_{\!\!,}\tilde ao}\\\begin{vmatrix}\sf1+x&\sf-1\\\sf3&\sf1-x\end{vmatrix}=0\\\sf(1+x)\cdot(1-x)-3\cdot(-1)=0\\\sf1-x^2+3=0\\\sf x^2=4\\\sf x=\pm\sqrt{4}\\\sf x=\pm2\\\sf S=\{-2,2\}\end{array}}$