Aa linear system is consistent if and only if the rightmost column of the augmented matrix ▼ is not is a pivot column. that is, if and only if an echelon form of the augmented matrix has ▼ of the form [0 0 b] with b nonzero.

Can someone plz me understand how to do these. plz, show work.in exercises 1-4, rewrite the expression in rational exponent form.[tex]\sqrt[4]{625} \sqrt[3]{512} (\sqrt[5]{4} )³ (\sqrt[4]{15} )^{7}\\ (\sqrt[3]{27} )^{2}[/tex]