A company's costs can be modelled by the function C(x)=1600−20x+0.1xˆ2 for 40≤x≤200, where x is the number of units produced per week. How many units should the company produce per week to minimise its costs?

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]