F.1~Mathsmatics Homework~~Fast

1.
n+2 = 2/9n-1/3
9xn+9x2 = (2/9n)x9-(1/3)x9
9n+18 = 2n-3
9n = 2n-21
7n = -21
n = -3

2.
3/4t = 4/3(t-7)
3/4t = 4/3t-7x4/3
3/4t = 4/3t-9/1/3 [4/3t-(9又3分之1)]
(3/4t)x12 = (4/3t)x12 - (9/1/3)x12
9t = 16t-112
7t = 112
t = 16

3.
x-1/5-4-x/2-2 = 0
x-1/5-x/2 = 4+2
10x-(1/5)x10-(x/2)x10 =6x10 　　　10乘ｘ怕你唔明所以直接打１０ｘ
10x-2-5x = 60
5x = 62
x = 12.4

1)
n+2 = 2/9n-1/3
2+ 1/3=2/9n -n
2=2/9n -n
2/2=9n-n
1=8n
1/8=n
2)
3/4t = 4/3(t-7)
3/4=4t/3(t-7)
3/4=4t/(3t-21)
3(3t-21)/4=4t
9t-63=4(4t)
9t-63=16t
-63=16t-9t
-63=7t
-63/7=t
-9=t
3)
x-1/5 - 4-x/2 - 2 = 0
x-1/5 - 4-x/2=2
x-1/5 - (4-x)=2x2
x-1/5 - 4+x=4
x-1/5 +x=4+4
(x-1)+x=8x5
x-1+x=40
2x=41
x=41/2