1.Assume y varies directly x and x varies directly z .When z=2,x=4 and when x=5,y=30.(a)1.Express x in terms of z.
2.Express y in terms of x.
3.express y in terms of z .
(b)Find the value of y when z=5.
2.Assume m-3 varies directly as n .When n=2,m=14.
(a)Find an equation connectting m and n .
(b)Find the value of m when n=5.
(c)Find the value of m when n=m-4.
MATHS(Variation)
2007-02-25 6:50 pm
回答 (1)
2007-02-25 7:13 pm
✔ 最佳答案
1a1)Let x=kz
when z=2, x=4
4=2k
k=2
∴x=2z
1a2)
Let y=k'x
when x=5, y=30
30=5k'
k'=6
∴y=6x
1a3)
Put x=2z into y=6x
y=6(2z)
y=12z
1b)
when z=5
By (a3),
y=12(5)
y=60
2a)
Let m-3=kn
when n=2, m=14
14-3=2k
11=2k
k=5.5
∴m-3=5.5k
2b)
when n=5
By (a)
m-3=5.5(5)
m-3=27.5
m=30.5
2c)
when n=m-4
m-3=5.5(m-4)
m-3=5.5m-22
-4.5m= -19
m= 4.22, cor to 3 sig. fig.
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