Question

Resolva:

a) ( 5,0.10^2).(6,0.10^-3)

b) ( 2,4.10^5) : (3,0.10^-2)

c) [(1,2.10^2) : (2,0.10^-4)]. (3,0.10^-6)

Answer 1

$= [(1,2*10^2) : (2,0*10^{-4})]* (3,0*10^{-6})$Oi Geovanna. :)


a) ( 5,0.10^2).(6,0.10^-3) =
$=( 5,0*10^2)*(6,0*10^{-3} ) \\ =(5*100)*(6* \frac{1}{10^{3}}) \\ =(500)*(6* \frac{1}{1000}) \\ =(500)*(\frac{6}{1000}) \\ = \frac{3000}{1000} \\ =3$

b) ( 2,4.10^5) : (3,0.10^-2)
$=( 2,4*10^5) : (3,0*10^{-2}) \\ \\ = \frac{(2,4*100000)}{3* \frac{1}{10^2}} \\ \\ = \frac{(240000)}{\frac{3}{100}} \\ \\ = (240000)}*{\frac{100}{3}} \\ \\ = (80000)}*{100} \\ =8000000$

c) [(1,2.10^2) : (2,0.10^-4)]. (3,0.10^-6)
$= [(1,2*10^2) : (2,0*10^{-4})]* (3,0*10^{-6})$

Qual das duas operações faremos primeiro? A divisão ou a multiplicação?
Olhe os conjuntos de operações... A ordem de resolução é sempre:
"parêntesis, colchetes, chaves"!

$= [(1,2*10^2) : (2,0*10^{-4})]* (3,0*10^{-6}) \\ =[(1,2*100):(2* \frac{1}{10000} )]*(3* \frac{1}{1000000} ) \\ =[120: \frac{1}{5000} ]* \frac{3}{1000000} \\ \\ = [120*\frac{5000}{1}]* \frac{3}{1000000} \\ \\ = 600000 * \frac{3}{1000000} \\ \\ = 6*\frac{3}{10} \\ \\ = \frac{18}{10} \\ \\ =1,8$


Atenção com os detalhes!
Regras gerais:

$a^{-n} = \frac{1}{a^n}$

$a: \frac{b}{c} =a* \frac{c}{b}$

Abraços.