4條中一數學問題,麻煩解答

[匿名]

2012-08-06 8:29 pm

1.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 ?

2.Ann had a bag of glass beads. She used half of the beads to make a necklace. She and his 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.

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

回答 (1)

用戶46949

2012-08-08 7:51 pm

✔ 最佳答案

Let $x be the cost of the rest (7-3) ceramic cats
$(x+3) be the cost of 3 more expensive ceramic cats
4x+ 3(x+3) = 100-7
4x+3x+9=93
7x=84
x=12
4 ceramic cats cost $12 each //
& 3 ceramic cats cost $15 each //

2. Let x be the original number of glass beads
(1/2)x + (1/6)x + (1/7)x = x -16 (x 42)
21x +7x + 6x = 42x -672
8x=672
x=84

the original number of glass beads is 84 //

3a. PQ is a vertical line
the x's coordinates of two points are the same
a=-5
3b. 3-b= +/- 5
b=8 or b=-2

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