数学问题，大家讨论•••

yaoyaomama

回复 山谷无回声 的帖子

在中国木有学过模型的啊..只会代数

yaoyaomama

山谷无回声 发表于 17-6-2011 13:13
中国的小学都教代数？比新加坡还落后？ 要不他们怎么解类似的题。

其实模型方法也不是好的方法， 原因是 ...

呵呵，我女儿下楼买饭去了。
在中国的小学好象学的是画大括号那种方法吧？这边是画方框，估计大同小异。现在中国孩子学得越来越深了，代数，方程，什么勾股定理八成都要在小学基本上都得掌握了。

meidance

回复 山谷无回声 的帖子

我支持你的观点。
数学，在小学阶段，是思维方法的训练。
如果把代数加上了就把孩子的脑袋搞僵化了。
当然，我也不能免俗。孩子到小六时，如果不能很好地掌握模型，就学点代数吧，有利于冲高分。
所以，我认为：如果你是家长，不要过早给孩子学代数。如果你是孩子会代数不是你的错。

yaoyaomama

我们是在国内的时候老师完全已经教过了，呵呵，我觉得数学这个东西自己教还真有些困难，如果家长本身就是数学老师的话那单说，我是不主张自己教的。数学这东西真不能勉强，完全是思维的东西，定论不了孩子的智商问题。我女儿是超级喜欢数学，爱做题，爱研究，我是见数就晕，已经直接还给老师啦，哈哈。

yaoyaomama

meidance 发表于 17-6-2011 13:23
回复 山谷无回声 的帖子

我支持你的观点。

恩，不错。不过我的观点是，要取决于孩子，如果孩子有能力就继续往前赶，不要停留，如果校内的还学不明白，就一定要打好基础，不可操之过急。

欢迎好运

Sava had some money. After spending $10 on 3 writing pads and 7 pencils, he would be short of $0.40 if he were to buy 1 more writing pad. If he were to buy 1 more pencil, he would have $0.60 left.
A) How much did each writing pad cost?
B) How much did Siva have at first?

A)$0.40+$0.60=$1
3*$1=$3
$10-$3=$7
7+3=10
$7/10=$0.70
$0.70+$1=$1.70

B)$10+$1.70-$0.40=$11.30 or

$10+$0.70+$0.60=$11.30

欢迎好运

楼上是我女解的题，我用的是代数如下：
1）3X+7Y=$10
2)  4X+7Y=Z+$0.4
3) 3X+8Y=Z - $0.6
2)-3)
X-Y=$1
   X=Y+$1
3(Y+$1)+7Y=$10
                 Y=$0.7
                 X=$1+$0.7=$1.7
3X$1.7+8X$0.7+$0.6=$11.3            

静雯

欢迎好运 发表于 5-6-2011 19:51
我女儿的数学问题，第一道：
Three boys,Aron,ben and charlie shared the cost of a birthday present for ...

Sorry for late reply.  
Although you've got the answer, I list my working as following: (Thanks to these who provide answers)
Problem 1:
A : (B+C)=1:3,    B : (A+C)=1:5,   
1+3=4, 1+5=6,
The Least Common Multiple for 4 & 6 is 12.
Let A's share be 3u, B's share be 2u, then C's share will be 7u.
7u-2u=5u=$50,
u=$10.
12u=$120.
Problem 2:
Four drinks cost as much as 3 chicken wings.     (1)
Five drinks cost $2.80 more than 2 chicken wings.  (2)
Five drinks equal to one drink plus 4 drinks. According (1), we can get one drink plus 3 chicken wings cost $2.80 more than 2 chicken wings. That is one drink plus one chicken wing cost $2.80.
$42/$2.80=15.

静雯

欢迎好运 发表于 6-6-2011 00:14
Xavier,Yati and Zul each had a certain number of stickers.At first,Yati had 200 stamps more than Xav ...

Solution:
(You'd better draw a model according"At first,Yati had 200 stamps more than Xavier"&"After Yati gave away 1/8 of her stamps to Xavier,she had 60 fewer stamps than Xavier", then you can understand well)
                     

From the model, we can observe Y gave 130 stamps to X.
That means 1/8 of Y=130. So Y=130*8=1040.
Then X=1040-200=840.
Z=1040*3/4=780.
Originally, X:Y:Z=840:1040:780=42:52:39.

静雯

shima 发表于 17-6-2011 11:01
回复 静雯 的帖子

请教一道数学题：

Solution:
According to "he would be short of $0.40 if he were to buy 1 more writing pad. If he were to buy 1 more pencil, he would have $0.60 left. ", we can get 1 writing pad costs $0.40+$0.60=$1.00 more than 1 pencil.
So 3 writing pads cost $3 more than 3 pencils. 3 Pads = $3+ 3 Pencils
According to the problem, 3 writing pads and 7 pencils cost $10. 3 Pads + 7 Pencils = $10
3 Pads = $3+ 3 Pencils ==> 3 Pads + 7 Pencils =$3+10 Pencils =$10
1 Pencil=$0.70
1 Writing Pad=$1.70
Sava had $10+$0.70+$0.60=$11.30 at first.