summer revision

2010-08-27 3:05 am

Find units digit of athe expression (5x2)+(5x4)+(5x6)+(5x8)+...+(5x998).
點計 ? 要解釋 answer

in a bookstore the number of chinese books is 50 more than twice the number of english books. if there are 350 chinese books, find the number of english books in the bookstore.問咩?點計 ? 要解釋 answer

The coordinate of the vertices of a trapezium areA(-2,-1),B(5,-1),C(3,2) and D(-1,2) respectively. Find the area of the trapezium.問咩?點計 ? 要解釋 answer

Given that the distance between A(-5,-2)and B(x,-2) is 6 units. Are the coordinates of B unique ?問咩?點計 ? 要解釋 answer

回答 (1)

Noelle

2010-08-27 3:57 am

✔ 最佳答案

1. (5x2)+(5x4)+(5x6)+(5x8)+...+(5x998)
=10+20+30+40+...+4990
=(10+4990) x (998/2)
=5000x499
=2495000

2. Let c be the number of chinese books and e be the number of english books.
c - 50 = 2e
(350) - 50 = 2e
2e = 300
e = 150 //
Therefore, there will be 150 of english books.

3. trapezium 梯形
Formula of area of trapezium: (upper width + lower width) x height / 2
I recommend you to draw a x-y graph on a graph paper to plot the diagram as this is a question of coordinates (x-axis and y-axis)
={[3-(-1)]+[5-(-2)]} x [2-(-1)] / 2
=(4+7) x 3 / 2
=33/2
=16.5 //

4. The x-axis of B is either -5 - 6 = -11 or -5 + 6 = 1
Unique 獨一无二
No, because there can be two possibilities of the x-axis.

If you don't understand what the questions are asking, you better use a dictionary or ask your teacher.

2010-08-31 18:50:47 補充：
啊？！我用開搜狗打字，沒轉回繁體。那個‘独一无二’係我自己打的，沒用字典。

參考: me myself

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