(UFGO) Simplificando a expressão $\phantom{X}\dfrac{\;a^2\,+\,a\;}{\;b^2\,+\,b\;}\centerdot \dfrac{\;a^2\,-\,a\;}{\;b^2\,-\,b\;}\centerdot \dfrac{\;b^2\,-\,1\;}{\;a^2\,-\,1\;}\phantom{X}$ obtém-se:
a)
$\,\dfrac{\;a\;}{\;b\;}\phantom{X}$
b)
$\,\dfrac{\;b\;}{\;a\;}\,$
c)
$\,\dfrac{\;a^2\;}{\;b^2\;}\,$
d)
$\,\dfrac{\;b^2\;}{\;a^2\;}\,$
e)
$\,\dfrac{\;ab\;}{\;b\;}\,$
