Maths F.3 urgent!!

2014-02-10 12:22 am

1.The monthly profits (in HK dollars) of Excellent Company from Jan to May 2010 are as follows: 53000,66000,73000,54000,64000
Find the arithmethic mean of the monthly profits in the above period.

2.Vivian walks along a path AB of slope 1/4. If the vertical distance BC is 12m, find the horizontal distance AC.

3. VABCD is a right pyramid with a square base ABCD. ABCD is a horizontal plane. E is the point of intersection of AC and BD. M is the midpoint of AB. Name the angle between the plane VAB and the plane ABCD.

4.Solve the inequality 3x + 1 >_ 10

5. Make X be the subject of the fomula y= X / 1 + X

6. Factorize X^(2) -7X +10

7. Factorize 4X^(2) -4X + 1

回答 (1)

知足常樂

2014-02-10 12:40 am

✔ 最佳答案

1.
The arithmethic mean of the monthly profits in the above period is (53000 + 66000 + 73000 + 54000 + 64000) ÷ 5 = $62000

2.
Slope = (vertical distance) ÷ (horizontal distance)
1/4 = (12 m)/AC
AC = 4 × 12 m = 48 m

3.
The angle between the plane VAB and the plane ABCD is ∠VME.

4.
3x + 1 ≥ 10
3x + 1 - 1 ≥ 10 - 1
3x ≥ 9
3x ÷ 3 ≥ 9 ÷ 3
x ≥ 3

5.
y = X / (1 + X)
y(1 + X) = X
y + yX = X
y = X - yX
y = X(1 - y)
X = y/(1 - y)

6.
　X² - 7X + 10
= X² - (2+5)X + (2×5)
= (X - 2)(X - 5)

7.
　4X² - 4X + 1
= (2X)² - 2(2X) + 1
= (2X - 1)²

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