The variables x, y, and z represent polynomials where x = a, y = 3a – 5, and z = a2 + 2. what is x2y – z in simplest form? 2a2 – 5a – 2 3a3 – 6a2 – 2 –3a3 – 2 –3a2 – 2

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]