Resposta:

[tex]\textsf{Leia abaixo}[/tex]

Explicação passo-a-passo:

[tex] \mathsf{E=\dfrac{\overbrace{\sf(-1)^{19}}^{\sf-1}-\overbrace{\sf(-1)^{37}}^{\sf-1}-\overbrace{\sf(-1)^{53}}^{\sf-1}}{2\cdot\underbrace{\sf(-1)^{71}}_{\sf-1}} } [/tex]

[tex] \mathsf{ E=\dfrac{(-1)-(-1)-(-1)}{2\cdot(-1) }} [/tex]

[tex]\boxed{\boxed{ \mathsf{E=-\dfrac{1}{2}}} } [/tex]