Question

Alguém pode me ajudar com essa questão? Preciso da explicação!​

Answer 1

Resposta:

Explicação passo-a-passo:

$(\dfrac{1}{a^{2}}-1).(\dfrac{1-a}{a+1}-\dfrac{1+a}{1-a}).(1-\dfrac{a}{4})=\\\\\\=(\dfrac{1-a^{2}}{a^{2}}).(\dfrac{(1-a)^{2}-(1+a)^{2}}{(a+1).(1-a)}).(\dfrac{4-a}{4})=\\\\\\=(\dfrac{1-a^{2}}{a^{2}}).(\dfrac{1-2a+a^{2}-(1+2a+a^{2})}{(a+1).(1-a)}).(\dfrac{4-a}{4})=\\\\\\=(\dfrac{1-a^{2}}{a^{2}}).(\dfrac{1-2a+a^{2}-1-2a-a^{2}}{(a+1).(1-a)}).(\dfrac{4-a}{4})=\\\\\\=(\dfrac{1-a^{2}}{a^{2}}).(\dfrac{-4a}{(a+1).(1-a)}).(\dfrac{4-a}{4})=$

$=(\dfrac{(1-a).(1+a)}{a}).(\dfrac{-1}{(a+1).(1-a)}).(4-a)=\\\\\\=(\dfrac{1}{a}).(\dfrac{-1}{1}).(4-a)=\\\\\\=(\dfrac{-(4-a)}{a})=\\\\\\=\dfrac{a-4}{a}=\\\\\\=\dfrac{a}{a}-\dfrac{4}{a}=\\\\\\=1-4.a^{-1}$

Item b)