中三負指數問題

指數律 :a ^ - b= 1 / (a^b)所以 (5/3) ^ -2= 1 / [(5/3)^2]= 1 / (25/9)= 9/25
方法二 :(5/3) ^ - 2= (5^-2) / (3^-2)= (1/5^2) / (1/3^2)= (1/25) / (1/9)= 9/25
方法三 :(5/3) ^ -2= ((5/3) ^ - 1)^2= (3/5) ^ 2= 9/25

2010-10-20 20:24:48 補充：
(a^2 x b^-2)^-1 / a^-3

= (a^-2)(b^2) / a^-3

= [a^(-2 - (-3))] b^2

= ab^2

(5/3)^-2
5^-2/3^-2
3^2/5^2
9/25