Lista de exercícios do ensino médio para impressão
After subtracting $\phantom{X}\dfrac{5}{8\;-\;3\sqrt{7}}\phantom{X}$ from $\phantom{X}\dfrac{12}{\sqrt{7} \;+\;3}\phantom{X}$ the result is:
a)
$81 - 4\sqrt{7}$
b)
$22 + 21\sqrt{7}$
c)
$-22\;-\;21\sqrt{7}$
d)
$41\sqrt{7}\;-\;81$
e)
none of these are correct.

 



answer: (C)
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