５０元一題(聽朝三點前前)

A man is 14 years older than his son.Two years later,his age will be twice that of his son.Find the age of his son now.


2(x-4)
----------- = -3
-3(x+3)



                                  1     2     3    4
Consider the sequence  ---  ; --- ; --- ; ---  ......
                                  2     3     4    5

(a) Write down the 5th , 6th , 7th and 8th terms of the sequence
(b) Express the Nth term of the sequence in terms of N
(c) What is the 100th term?

1         x          x        1
----   -  ----   =   ----  -  ----
4        2           4       8



3            5           1  
---(x+1) - ----  =  - ---- (x-2)
2            6           3

5 times a number is greater than 3 times the number by 4. Find the number.
Solution: Let x be the number

The length of a rectangle is 3 cm longer than its width.The perimeter of the rectangle is 30 cm.Find the length of the rectangle.


For a product, its marked price=$50, cost price=$40 and selling price=$36.
What percentage is the price marked up?

[ 本帖最後由 彤兒` 於 2008-8-20 09:22 PM 編輯 ]

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thz
請開sell po:)
歡迎再help xd

A man is 14 years older than his son.Two years later,his age will be twice that of his son.Find the age of his son now.
設現在兒x歲, 父x+14歲, 2年後兒x+2歲, 父x+16歲, x+16=2*(x+2)→x+16=2x+4→x=12

2(x-4)
----------- = -3
-3(x+3)
全式同乘以-3(x+3)→2(x-4)=-3*-3(x+3)→2x-8=9x+27→7x=-35→x=-5

                                  1     2     3    4
Consider the sequence  ---  ; --- ; --- ; ---  ......
                                  2     3     4    5

(a) Write down the 5th , 6th , 7th and 8th terms of the sequence
(b) Express the Nth term of the sequence in terms of N
(c) What is the 100th term?
(a)5/6, 6/7, 7/8, 8/9
(b)N/(N+1)
(c)100/101

1         x          x        1
----   -  ----   =   ----  -  ----
4        2           4       8

全式同乘以8化成整數便於計算→2-4x=2x-1→6x=3→x=1/2

3            5           1  
---(x+1) - ----  =  - ---- (x-2)
2            6           3

全式同乘以6化成整數便於計算→9(x+1)-5=-2(x-2)→9x+9-5=-2x+4→11x=0→x=0

5 times a number is greater than 3 times the number by 4. Find the number.
Solution: Let x be the number→5x=3x+4→2x=4→x=2

The length of a rectangle is 3 cm longer than its width.The perimeter of the rectangle is 30 cm.Find the length ofthe rectangle.
設長為x, 寬為x-3, 邊長為2*(x+x-3)=30→4x-6=30→4x=36→x=9

For a product, its marked price=$50, cost price=$40 and selling price=$36.
What percentage is the price marked up?

(50-40)/40*100%=10/40*100%=25% (唔確定...)

1     2     3    4
Consider the sequence  ---  ; --- ; --- ; ---  ......
                                  2     3     4    5

(a) Write down the 5th , 6th , 7th and 8th terms of the sequence
(b) Express the Nth term of the sequence in terms of N
(c) What is the 100th term?
(a)5/6, 6/7, 7/8, 8/9
(b)N/(N+1)
(c)100/101




↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑
我想問呢題果d 5/6, 6/7, 7/8, 8/9
係唔係姐係 六分之五,七分之六,八分之七同9分之八?

可吾可以詳細D講呢一題?
因為三個答案都唔係好明點求出尼..
THZ!

thanks :p 都係得閒做下. 收你25蚊 :ppp

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是六分之五,七分之六,八分之七同9分之八沒錯=]
"/"是"除以"的意思, 5/6=5除以6=6分之5

多謝哂呀.
錢sd緊比你:)
不過請唔好del答案住...]]