本區搜索:
Yahoo!字典
打印

[Core] 數學廢

[隱藏]

數學廢

1.Mrs chan used $60 to buy some mangoes. If the price of each mango is increased by $1 she will buy 2 mangoes less with $60 . Find the original price of each mango
2.mr chan distributes 120 cups evenly into a certain number of boxes . If 3 fewer boxes are used , each boyx has to contain 2 more cups .how many boxes are there originally?
3. The area of an isosceles right -angled triangle is x/2 cm^2 . If the base increased by 2 cm and height is decrease d by 1 cm, the area of new triangle is 14 cm^2. Find x
求好心人比條式我
我諗左好耐



   

TOP

Question 1 solution

Let x be the original price of the mangoes.
Let y be the original amount of mangoes.

xy=60---(i)
(x+1)(y-2)=60---(ii)

In (i),
xy=60
y=60/x---(iii)

Sub (iii) into (ii)
(x+1)(60/x-2)=60
x=5 or -6(rejected)

Therefore, the original price of each mango is $5.

TOP

Question 2 solution

Let x be the original number of boxes used.
Let y be the original no of cups one box contains.

xy=120---(i)
(x-3)(y+2)=120---(ii)

In (i),
xy=120
y=120/x---(iii)

Sub (iii) into (ii)
(x-3)(120/x+2)=120
x=15 or -12

Therefore, the original no of boxes used is 15.

TOP

要用more about quadratic equations



TOP

Push

TOP

推多一次

TOP

點解無人答

TOP

再推多一次

TOP

Question 3 solution

let a cm be the base of the original triangle'
(a+2)(a-1)/2=14
a^2+a-2=28
a^2+a-30=0
a=5 or -6(rejected)

so x = a^2
        =25

TOP

仲有第1,2題未答到,再換推一推

TOP

重要聲明:小卒資訊論壇 是一個公開的學術交流及分享平台。 論壇內所有檔案及內容 都只可作學術交流之用,絕不能用商業用途。 所有會員均須對自己所發表的言論而引起的法律責任負責(包括上傳檔案或連結), 本壇並不擔保該等資料之準確性及可靠性,且概不會就因有關資料之任何不確或遺漏而引致之任何損失或 損害承擔任何責任(不論是否與侵權行為、訂立契約或其他方面有關 ) 。