Maths題目...help:)

[匿名]

2013-01-02 2:14 am

1.2x+3-(3x-2)=6 x=?

2.-0.5,-2,-4.5,-8 Find the general term

3.Mrs.Wong bought 11apples and 13oranges for $84. If the price of eacjh orange is lower than five times of each apple by $14, what is the price of each of apple

4.Amy usually spends her pocket money on three parts: meal, transportation and clothing. If her spending on meal is more than three times of her transportation by $200, half of her transportation is the same as her spending on clothing, and she has $1400 each month. How much does she spend on clothing?

回答 (1)

成

2013-01-02 2:46 am

✔ 最佳答案

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

2.)Note that
-0.5,-2,-4.5,-8
=-1/2,-4/2,-9/2,-16/2
=-(1)^2/2,-(2)^2/2,-(3)^2/2,-(4)^2/2
所以
-n^2/2就係general term

3.)Let x be the price of each of apple, y be the price of each of orange,
11x+13y=84............1
5x-y=14[因為佢話一個橙便宜過5個蘋果$14]
5x-14=y..............2
Sub 2 to 1
11x+13(5x-14)=84
11x+65x-182=84
76x=266
x=$3.5(好貴)
So,$3.5 is the price of each of apple.(其實橙都係賣$3.5一個)

4.)Let x,y,z be the pocket money she spend on meal, transportation and clothing respectively(分別地),
x-3y=200
y/2=z
x+y+z=1400

x-3y=200寫成 x=200+3y.........1
y/2=z寫成 y=2z.....................2
x+y+z=1400...........................3
Sub 1 to 3
200+3y+y+z=1400
200+4y+z=1400.....................4
Sub 2 to 4
200+8z+z=1400
9z=1200
Z=$400/3
So $400/3 is the pocket money she spend on clothing.
我英文唔好如果解過我即刻計過
希望幫到你

2013-01-01 18:46:28 補充：
如果解錯

參考: 自己

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