Math problems, need some help.?

2011-09-08 10:13 am

1)One group of children want to buy a ball. If each of them would give 20$, not reach 40 $, but if each give 25$, it still remain 20 $. a) what is the ball's price b) how many kids are in the group.
2) If we place the students of a classroom 3 each in the desk, it will remain 3 empty desk, but if we place them 2 in the desk they 3 students will not have a place to sit. a) how many students are in the classroom b) how many desks are in the classroom?
3) If x+y = 2√2 and x*y=1 to demonstrate x2+y2

回答 (5)

[匿名]

2011-09-08 11:01 am

✔ 最佳答案

Let the no of children be x

Cost of ball = 20x +40

Cost of ball is also = 25x -20

20x +40 = 25x -20

5x=60

x = 12

ANSWER = a-) 280 $ ( 25x-20) b) kids = 12

CHECK
Cost of ball = 280$
20X12 = 240$
Short by 40$
25X12 = 300$
20 $ excess

2) Let the no of students be x and the no of desks be y
x= 3 (y -3)

3y - x = 9 (A)

2y +3 = x (B)

Replace for x from B in A

3y - ( 2y+3) = 9
y -3 = 9
y = 12
x = 27
ANSWER a) 27 students b) 12 desks
CHECK
27/3 = 9
12-9 = 3 desks empty
12X2 = 24
27-24 = 3 students without desks

3) x+y = 2\/2
SQUARE BOTH SIDES

x^2 + y^2 + 2xy = 8
x^2 + y^2 + 2*1 = 8

x^2 + y^2 = 6 ANSWER

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[匿名]

2011-09-08 10:28 am

honestly I can't understand this. not to be rude but please check your grammar.

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[匿名]

2011-09-08 10:21 am

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[匿名]

2011-09-08 10:18 am

Why don't you try an English class instead of arithmetic?

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