難題6條....help...help plz

2008-08-22 5:45 am

1.某人站於水平面上10m,而海則深26m,,該人與海底的垂直距離為多少???

2.+3有4份之1-﹝+2有2份之1減-2分之1）除4份之-1

3.（負4份之3）*（負4份之1﹞*（負8份之7）除（負16份之7﹞(((整個為負數,,唔係just 分母係負數...

4. 3 years ago Mr Wong was three times as old as his son 7 years later Mr Wong will be twice as old as his son How old is Mr Wong now???

5.一個圓形花圃的四周被籬笆圍繞着若籬笆長度是125.6m花圃的半徑是多少???

6.一個圓形跑道半徑是14m 某人沿着跑道跑了10個圈那麼他跑了多遠
兀=22/7

回答 (1)

o0kenchung0o

2008-08-24 6:53 am

✔ 最佳答案

1)設水平面高度為0m
10m - ( - 26m)
= 36m
人與海底的垂直距離為36m

2)注意帶分數寫法!!唔係有!!係又!!
3+1/4 - [ 2+1/2 - 1/(-2) ] / [(-1)/4]
= 3+1/4 - ( 2+1/2 + 1/2 ) / [(-1)/4]
= 3+1/4 - [(-3)/4]
= 3+1/4 + 3/4
= 4

3)整個為負數,,唔係just 分母係負數<<這一到你似乎有誤會
-a a a
一 = 一 = - 一
b -b b
所以係冇分別的
[-(3/4)] * [-(1/4)] * [-(7/8)] / [-(7/16) ]
= (3/16) * [-(7/8)] / [-(7/16) ]
= [3/(-7)] * [-(7/8)]
= 3/8

4)這一條是問3年前黃先生的年齡是兒子的三倍,7年後黃先生的年齡將會是兒子的2倍,問黃先生現在的年齡嗎?
設黃先生現年x歲
[(x-3)/3]+3=[(x+7)/2]-7=兒子現在的年齡
2(x-3)+18=3(x+7)-42
2x-6+18=3x+21-42
2x+12=3x-21
x=33
黃先生現年33歲

5)設花圃半徑為x
2兀x = 125.6m
6.28x = 125.6m
x = 20m
花圃半徑為20m

6)10 * 2兀 * 14m
= 140m * 2 * 22/7
= 20m * 2 * 22
= 880m
他跑了880m

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