f.2 maths(20 pts)

15b^12 / 18b^5

.....(15) b^12
= ------------------
.....(18) b^5

.....(15)...... b^12
= ------- x ---------
.....(18) .......b^5



.....5...... b^12
= ----- x ---------
.....6 .......b^5

.....5
= ----- x b^12 x b^-5
.....6

.....5
= ----- x b^(12 -5)
.....6

.....5
= ----- (b^7)
.....6

.....5 b^7
= ---------
........6

15b^12
18b^5
= 5b^12
6b^5
= 5b^(12-5)
6
= 5b^7
6
-------------------

5b^7 over 6

2006-10-26 13:40:36 補充：
15b^12 / 18b^5= (15/18) x (b^12/b^5)= 5/6 x b^(12-5)= 5b^7 / 6