Respostas

2014-02-17T18:38:55-03:00
A) 0,8 =  \frac{8}{10}  =  \frac{4}{5}

 (\frac{4}{5} )^x =  (\frac{4}{5} )^-^1

x = -1

B) 5^-^2^x^+^3 < 25

5^-^2^x^+^3 < 5^2  simplifica o 5

-2x + 3 < 2
-2x < -1      (-1)

2x < 1

x <  \frac{1}{2}
1 5 1