設y隨x反變,當x= a時,y=3;當x=b時,y=4.
a)求a:b
b)當x=a+b時,y的值是多少?
中4數學,唔該列詳細步驟,thx
2008-03-03 12:01 am
回答 (2)
2008-03-03 12:10 am
✔ 最佳答案
y=k/x3=k/a-------------------A
4=k/b-------------------B
4A=3B=12
4k/a=3k/b
3a=4b
a:b=4:3
y=k/(a+b)
y=k/(a+0.75a)
y=k/1.75a
y=(1/1.75)k/a
y=(1/1.75)*3
=12/7
2008-03-03 12:50 am
Since y directly as 1/x
3 = 1/a
a = 1/3
4 = 1/b
b = 1/4
a : b = 1/3 : 1/4
= 4 : 3
when x = a + b,
y = 1/(1/3 + 1/4)
y = 1/[4/12 + 3/12]
y = 1/7/12
y = 12/7
3 = 1/a
a = 1/3
4 = 1/b
b = 1/4
a : b = 1/3 : 1/4
= 4 : 3
when x = a + b,
y = 1/(1/3 + 1/4)
y = 1/[4/12 + 3/12]
y = 1/7/12
y = 12/7
收錄日期: 2021-04-20 13:46:26
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