中四Variation問題

1.Z=a+kx

2.P=b+h/√(t)

3.Y=au+kv

這是部分比的問題

1.
z is partly constant and partly varies directly as x.
即z一部份是constant , 一部份是正比於x
而中間要將兩部份加起來,即是
Z=a+kx

2.
P is partly constant and partly varies inversely as the square root of t.
同第一題一樣 , 不過注意square root 即係√(t)
P=b+h/√(t)

3.
Y partly varies directly as u and partly varies directly as v.
一部份正比於u , 一部份正比於v
技巧跟第1,2題一樣的
Y=au+kv

Answer:
1. z = a + kx
2. P = a + k/(t^2)
3. Y = au + bv

逢見到 partly 呢個字就用「+」(代表條式由兩部分組成)

例子:
Let a, b be the constants.
x varies directly y : x = ay
x varies inversely as y : x = a/y
x partly varies directly as y and partly varies directly as z = x = ay + bz

如果佢話 'is a constant' 咁就淨係寫 constant 個字母代表就得

1. z=(k1) + (k2)x where K1 and k2 are not equal to 0

2. P = (k1) + (k2)/sqrt (t) where K1 and k2 are not equal to 0

3. Y = (k1)u + (k2)v where K1 and k2 are not equal to 0