F.1數 急**功課

　　x
1)　－ + 2 = 4(x+1)
　　3

x/3 + 2 = 4x +4
x/3 - 4x = 4-2
x (1/3 - 4) = 2
x = 2/(-11/3)
x = -6/11


2)The LCM of 24 , 60 and x is 240. Find the smallest possible value of x.
　（24: (2 ³ )(3)　　）
　〔60: (2 ²) (3) (5)　）

smallest possible value = 2^4 = 16

because the LCM of 24 and 60 is 2^3 x3 x5 = 120
therefore, to get at least 240 for the LCM of 3 numbers,
it should x2 again.
which is 2^4. there are 4 possible answers that you could still get 240 as the LCM of those 3 numbers.
they are:
2^4 = 16
2^4 x3 = 48
2^4 x5 =80
2^4 x3 x5 =240

and 16 is the least number. therefore, 16 is your answer.

3)Ben has $1500 to buy 2 coats and some shirts. If the price of shirt is $120 and that of a coat is $250, find the MAXIMUM (最大) number of shirts that Ben can buy.

($1500 - 2x120) / 250
=5.04

therefore, ben could buy 5 coats at most.

2007-10-22 20:14:27 補充：
o god! i read the question wrongly!!it should be:3)($1500 - 2x250) / 120=8.33therefore, ben could buy 8 shirts at most.

1)x/3+2=4(x+1)
x/3=4x+4-2
x/3=4x+2
x=3(4x+2)
x=12x+6
11x=-6
x=-6/11

2)240=2^4*3*5
x=16

3)$(1500-2*250)/$120
=$1000/$120
=8 shirts...$40
So Ben can buy 8 shirts at most.