f4..maths

4a^-2=9
4/a^2=9
...a^2=4/9
.......a=士2/3

2007-02-21 23:40:23 補充：
士= 正負

2007-02-21 23:41:43 補充：
4a^-2=94/a^2=9...a^2=4/9.......a=±2/3

4a^-2=9
1/a^2=9/4
1/a=3/2
a=2/3

-2log a =log 9/4

a =0.66666666.....