中二聯立方程一條!急...

2/a + 3/b = 5 .............1
3/a + 5/b = 9 .............2

1 X 3

6/a + 9/b = 15 ..............3

2 X 2

6/a + 10/b =18 ..............4

3 - 4

9/b - 10/b = -3
-1/b = -3

b=1/3

sub b=1/3 into 2/a + 3/b = 5

a= -1/2

2/a+3/b=5----------------(1)
3/a+5/b=9----------------(2)
(1)X3
6/a+9/b=15------------------(3)
(2)X2
6/a+10/b=18-------------------(4)
(4)-(3)
10/b -9/b=18 -15
(10 -9)/b=18 -15
1/b=3
1=3b
b=1/3------------------(5)
(5)代入(1)
2/a+3/1/3=15
2/a+3X3=15
2/a+9=15
2/a=6
2=6a
a=2/6
a=1/3

2007-06-16 20:13:12 補充：
後面看錯了,(5)代入(1)2/a+3/1/3=52/a+3X3=52/a+9=52/a= -42= -4aa=2/-4a= -1/2

2/a + 3/b = 5
(2b+3a)/(ab) = 5
a = (2b)/(5b-3) →@


3/a + 5/b = 9
3/@ + 5/b =9
b = 1/3

2/a + 3/b = 5
a = -1/2