幾條maths 小6 ！！(緊急)(10點)

1.
a-b=72 &
a=9b so,
9b-b=72
b=9
小數=9

2.
90(1/5) x234 + 9(4/5)x234=
= 234 X <45(1 / 5) + 4(9 / 5)>
= 234 X 100
= 23400

3.
20y+7+y=14-6y,
20y+y+6y=14-7
27y =7
y = 7 / 27

ans :
1) Let X be a larger number, Y be a smaller number
X - Y = 72 -----(1)
X = 9Y ------(2)
Put (1) into (2)
9Y - Y = 72
8Y = 72
Y = 9

2) 90又1/5 X 234 + 9又4/5 X234 = ( 90 x 5 + 1 + 9 x 5 + 4 ) x 234 / 5 = 500 x 234 / 5
= 100 x 234 = 23400

3) 20y+7+y=14-6y
21y + 6y = 14 - 7
27y = 7
y = 7 / 27

1.大小兩數之差是72,大數是小數的9倍,求小數． =?
設大數為x,小數為y
x-y=72 x=9y

9y-y=72
8y=72
y=9

x-9=72
x=81

大數為 81 , 小數為 9。


2.90又1/5 X 234 + 9又4/5 X234 =?
451/5x234+49/5x234
=234(451/5+49/5)
=234(500/5)
=234(100)
=23400




3. 20y+7+y=14-6y, y=?
21y+7=14-6y
21y+6y=14-7
27y =7
y=7/27

1.
大-小=72----1
大=9小-------2

1-----9小-小=72
8小=72

小=9
大=81

2.
(90 1/5)X234+(9 4/5)X234
=(451/5+49/5)X234
=(451+49)/5X234
=500/5X234
=100X234
=23400

3.
20y+7+y=14-6y
21y+7=14-6y
21y+6y+7-7=14-7-6y+6y (两面都相等)
27y=7
y=7/27

QED

1)
設小數為x, 那麼大數就是 x+72.
大數÷小數 = 9
i.e. (x+72) ÷ x = 9
x+72 = 9x
72 = 8x
x = 9.
所以小數是9.
2)

圖片參考：http://i169.photobucket.com/albums/u209/lautszki/p6.jpg


3)
20y + 7 + y = 14 – 6y
20y + y + 6y = 14 – 7
(20+1+6)y = 7
27y = 7
y = 7/27

2007-07-10 13:27:41 補充：
小六應該還未學懂2個未知數的做法

2007-07-10 14:20:03 補充：
4.x (1- 1/4) = 9x3x/4 = 9x3x = 36x0 = 33xx = 0