form 4 maths - variation

圖片參考：http://i.imagehost.org/0713/ScreenHunter_05_Apr_16_22_47.gif


http://i.imagehost.org/0713/ScreenHunter_05_Apr_16_22_47.gif

2010-04-16 22:51:21 補充：
Correction:
http://i.imagehost.org/0986/ScreenHunter_06_Apr_16_22_50.gif

2010-04-16 22:52:27 補充：
19a)z=4x+ (24/開方y)

(b)x=5

p∝x ⇒ p=hx
q∝1/√y ⇒ q=k/√y

z=p+q
=hx+k/√y

For x=3 , y=4 and z=24: 6h+k=48____(1)
For x=−1 , y=36 and z=0: −6h+k=0___(2)

(1)−(2): 12h=48 ⇒ h=4 ∴k=24

z = 4x + 24/√y

When z=26 and y=16:
26=4x+(24/4)
x=5