f.3 數學題目 - Ans.fyi 參考答案

f.3 數學題目

＊回憶☆╮

2008-07-25 6:08 pm

1.Solve the following inequalities and represent their solutions graphically
a) 6x+4>16 or 3x-5<1

2.Bag A contains three oranges and two $5 coins. Bag B contains four oranges
and three $2 coins. If the value of Bag A is not higher than that of Bag B,
what is the minimum value of each orange?

3.The distance between A(a , 8) and B(4 , 2) is 10.Find the two possible
values of a.

4.A man on the ground finds the angle of elevation of the top of a building in
front of him to be 45°. If he walks 10m away from the building, the angle of
the elevation become 40°.find the he height of the building.

要有過程

回答 (1)

Wai Chiu

2008-07-25 7:40 pm

✔ 最佳答案

1a)
6x+4>16
6x>12
x>2

or

3x-5<1
3x<6
x<2

Graphically, like "T" , 下面指住 2 就 ok, 上面應該係實心黑點

2) let orange value as x
(BAG A) 3x+10 <= 4x+6 (BAG B)
4 <= x
x >=4

so, min value is 4

3) Phy. Them.

sq. (8-2) + sq. (a-4) = sq. 10
36+ sq. (a-4) = 100
sq. (a-4) = 64
a-4 = +/- 8
a=12 or a=-4

4) let the orginial distance between the man and the building as a,
the height of building as b,

tan 45°= b/a = 1
so, imply that's a=b

OR you can mentioned that since the elevation is 45°, whcih consist an isos, triangle, so the distance between the man and the buildling equal to the height of the building

10m far away :
tan 40° = height / org. distance + 10m
tan 40° = a / a+10
a = ???

(無計數機係手, 計唔到呢個答案)

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