英文數學題x7,請各位幫幫手！！

[匿名]

2014-07-09 10:42 pm

英文數學題x7,請各位幫幫手！！萬分感激！！

q1: 4(3m/5)-2m-8+=0 (*find m)

q2: c-5/6+3=2-c/8 (*find c)

q3: Ann had $100.She used part of her money to buy 7 ceramic cats, in which 3 of them are more expensive than the rest by $3.If she had $7 left,
how much do the two types of ceramic cat cost ?

q4: Ann had a bag of glass beads.She used half of the beads to make a
necklace.She and her sister then use 1/6 and 1/7 of the original number of
beads respectively to make two bracelets.If there are 16 glass beads left,find
the original number of glass beads.

q5: Last month,there were two 30 male students and 20 female students in the
chess class.The number of male students decreases by r% and the numder of
female students increases by r% in this month .If the number of male and
female students are the same in this month,find r.

q6: Two shops sell the same brand of chocolate at the same price.Today they
both cut down its price .Shop A decreases the price by 30% , and increases by 30% after a week.Likewise ,Shop B decreases its price by 40% , and increases by 40% after a week.Are the price of the chocolate at the two shops still the
same after a week?

q7: Given two points P(a,3) and the Q(-5,b), and PQ is a vertical line.
(a) Find the value of a .
(b) If the distance between PQ is 5 units , find two possible valuos of b.

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回答 (1)

fooks

2014-07-10 12:20 am

✔ 最佳答案

1.
4(3m/5) - 2m - 8 = 0
(12m/5) - (10m/5) - (40/5) = 0
12m - 10m - 40 = 0
2m = 40
m = 20

2.
(c - 5)/6 + 3 = (2 - c)/8
(c - 5)/6 + 18/6 = (2 - c)/8
(c + 13)/6 = (2 - c)/8
4(c + 13) = 3(2 - c)
4c + 52 = 6 - 3c
7c = -46
c = -46/7

3.
Let $c be the cost of each more expensive ceramic cat.
Then, the cost of each less expensive ceramic cat = $(c - 3)

100 - 3c - (7-3)(c - 3) = 7
100 - 3c - 4c + 12 = 7
7c = 105
c = 15
c - 3 = 12

The cost of each more expensive ceramic cat = $15
The cost of each less expensiveceramic cat = $12

4.
Let n be the original number of glass beads.

n - (1/6)n - (1/7)n = 16
(42/42)n - (7/42)n - (6/42)n = 16
(29/42)n = 16
n = 672/29

n is not an integer.
Thereis no solution, or there are mistakes in the question.

5.
30(1 - r%) = 20(1 + r%)
3(100 - r) = 2(100 + r)
300 - 3r = 200 + 2r
5r = 100
r = 20

6.
Net percentage change of the price of the chocolate A
= (1 - 30%) x (1 + 30%) - 100%
= 91% - 100%
= -7%

Net percentage change of the price of the chocolate B
= (1 - 30%) x (1 + 30%) - 100%
= 91% - 100%
= -7%

Hence, the price of the chocolate at the two shops still the same.

7.
(a)
The y-coordinates of all points in a vertical line are the same.
Hence, a = -5

(b)
√[(-5 + 5) + (3 - b)² = 5
(3 - b)² = 25
3 - b = 5 or 3 - b = -5
b = -2 or b = 8

參考: fooks

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