$25-26$ Express the integral as a limit of Riemann sums using right endpoints. Do not evaluate the limit$.$

$25.{\displaystyle \underset{1}{\overset{3}{}}}\sqrt[\phantom{2}]{4x^2}dx$

$26.{\displaystyle \underset{2}{\overset{5}{}}}(x^2\frac{1}{x})dx$