F.1 math(difficult)plzhelp

1a)
(2h-k)-(5h-9k)
= 2h - k - 5h + 9k
= (2-5) h + (9 - 1)k
= -3h + 8k

1b)
(x+4y-z)+(5x-4y+3z)
= x + 4y - z + 5x - 4y + 3z
= (1+5) x + (4-4)y + (3-1) z
= 6x + 2z

1c)
6(a+b)-4(a-b)
= 6a + 6b - 4a + 4b
= (6-4) a + (6+4) b
= 2a + 10b

2a)
28-2x = 3(x+1)
28 - 2x = 3x + 3
28 - 3 = 3x + 2x
25 = 5x
x = 25/5
x = 5

(b)
1/2x - 7 = 5 + x
1/2 x - x = 5 + 7
(1/2 - 1)x = 12
-1/2 x = 12
x = 12(-2)
x = -24

3a)
width = x - 7

3b)
[ (x-7) + x] * 2 = 74

3c)
[ (x-7) + x] * 2 = 74
x - 7 + x = 74/2
2x - 7 = 37
2x = 37 + 7
2x = 44
x = 22
Therefore, length of rectangle is 22 cm and the width of it is (22-7) = 15 cm

4)
Let the amount of money that Peter get be x dollars,
then the amount of money that Jack and Tom get is (x + 40) and (x + 40 + 210) dollars respectively.

x + (x + 40) + (x + 40 + 210) = 860
x + x + 40 + x + 40 + 210 = 860
x + x + x + 40 + 40 + 210 = 860
3x = 860 - 210 - 40 - 40
3x = 570
x = 570 / 3
x = 190

Therefore, Peter gets $ 190, Jack gets ($190+$40) = $230 and Tom gets ($230 + $210) = $440

1.a) 8k-3h
b) 2(3x+z)
c) 2(a+5b)
2.a) x=5
b) x=-24
3.a) x-7
b) 2(2x-7)=74
c) x=22, width=15cm, length=22cm
4.Tom=$440, Jack=$230, Peter=$190

1
a)(2h-k)-(5h-9k)
=2h-k-5h+9k
=8k-3h
b)(x+4y-z)+(5x-4y+3z)
=x+5x+4y-4y-z+3z
=6x+2z
=2(3x+z)
c)6(a+b)-4(a-b)
=6a+6b-4a+4b
=2a+10b
=2(a+5b)

2
a)28-2x=3(x+1)
28-2x=3x+3
5x=25
x=5
b)1/2x-7=5+x
1/2x=-12
x=-24

3
a)x-7
b)2x+2(x-7)=74
c)2x+2(x-7)=74
2x+2x-14=74
4x=88
x=22

4
if
Peter=x
Jack =x+40
Tom =x+40+210=x+250

x+x+40+x+250=860<------total
3x=570
x=280

2007-07-24 01:54:50 補充：
希望幫到你

1(a).(2h-k)-(5h-9k)
=2h-k-5h+9k
=8k-3h

1(b).(x+4y-z)+(5x-4y+3z)
=x+4y-z+5x-4y+3z
=6x+2z

1(c).6(a+b)-4(a-b)
=6a+6b-4a+4b
=2a+10b

2(a).28-2x=3(x+1)
28-2x=3x+3
3x+2x=28-3
5x=25
x=5

2(b).1/2x-7=5+x
1/2x-x=5+7
-1/2x=12
x=12X-2
x=-24

3(a).The width=x-7(cm)

3(b).2(x+x-7)=74

3(c).2(x+x-7)=74
2x-7=37
2x=44
x=22
Hence,the length of the rectangle=22cm,the width of the rectangle=15cm

4.Suppose Jack gets $x,Tom gets $x+210,Peter gets $x-40
x+x+210+x-40=860
3x=690
x=230
Hence,Jack gets $230,Tom gets $440,Peter gets $190.