D) -5/4

[tex][x^3+2y]\div [x-y]=[/tex]

[tex][(\frac{1}{2})^3+2\cdot (-1)]\div [\frac{1}{2}-(-1)]=[/tex]

[tex][\frac{1}{8}-2]\div [\frac{1}{2}+1]=[/tex]

[tex][\frac{1}{8}-\frac{16}{8}]\div [\frac{1}{2}+\frac{2}{2}]=[/tex]

[tex]-\frac{15}{8}\div \frac{3}{2}=[/tex]

[tex]-\frac{15}{8}\cdot \frac{2}{3}=[/tex]

[tex]-\frac{30}{24}=[/tex]

[tex]\boxed{-\frac{5}{4}}[/tex]

Resposta:

[tex]39.\\ \\ \\ \frac{x^{3}+2y }{x-y} \\ \\ para:\\ \\ x=\frac{1}{2}\\ \\ y=-1\\ \\ \\ \frac{(\frac{1}{2})^{3}+2.(-1) }{\frac{1}{2}-(-1) } =\\ \\ \\ \frac{\frac{1}{8}-2 }{\frac{1}{2}+1 } =\frac{\frac{1-16}{8} }{\frac{1+2}{2} } =\frac{\frac{-15}{8} }{\frac{3}{2} } =-\frac{15}{8} :\frac{3}{2} =\\ \\ \\ -\frac{15}{8} *\frac{2}{3} =-\frac{30}{24} =-\frac{5}{4} \\ \\ \\ resposta=-\frac{5}{4}[/tex]

Alternativa D) -5/4