a$.$ Evaluate ${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{x}{\sqrt[\phantom{2}]{x8}}dx$ using integration by parts.

b$.$ Evaluate ${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{x}{\sqrt[\phantom{2}]{x8}}dx$ using substitution.

c$.$ Verify that your answers to parts $($a$)$ and $($b$)$ are consistent.

a$.$ Use the integration by parts formula. Choose the correct answer.

A$.2x\sqrt[\phantom{2}]{x8}{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}2\sqrt[\phantom{2}]{x8}dx$

B$.2x\sqrt[\phantom{2}]{x8}-{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{2}{\sqrt[\phantom{2}]{x8}}dx$

C$.2x\sqrt[\phantom{2}]{x8}{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{2}{\sqrt[\phantom{2}]{x8}}dx$

D$.2x\sqrt[\phantom{2}]{x8}-{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}2\sqrt[\phantom{2}]{x8}dx$