GWD－６－３５

[kazue68jp]

Q35:
The operation ○ is defined by the equation x ○ y = (x-y)/(x+y), where y ≠ -x. If 3 ○ y = 5 ○ 4, then y =

A. 1/9
B. 4/15
C. 5/12
D. 12/5
E. 15/4


Answer:D

我猜O是減法,但是還是卡住了.

[wind31526]

Q35:
The operation ○ is defined by the equation x ○ y = (x-y)/(x+y), where y ≠ -x. If 3 ○ y = 5 ○ 4, then y =

A. 1/9
B. 4/15
C. 5/12
D. 12/5
E. 15/4


Answer:D

我猜O是減法,但是還是卡住了.

不用猜阿，直接把條件代進去就好了
(3-y) / (3+y) = (5-4)/(5+4) = 1/9
y= 24/10 =12/5

[kazue68jp]

原來如此,謝謝拉.