5條數學方程式題目 [數學高手請進~~]

6[2(2-y)-3y]=24
6[4-2y-3y]=24
6[4-5y]=24
4-5y=4y=0
9(2a-1)=3[4(1+2a)-5]-8a
9(2a-1)=3[4+8a-5]-8a
9(2a-1)=3[8a-1]-8a
9(2a-1)=24a-3-8a
18a-9=16a-3
2a=6
a=3
1/3(t+9)=1/3-0.5(t+3)
兩邊乘6
2(t+9)=2-3(t+3)
2t+18=2-3t-9
5t=-25
t=-5
(2n-5)/3=(n-10)/9
3(2n-5)=n-10
6n-15=n-10
5n=25
n=5
(x-1)/2=(x+1)/3+1
兩邊乘6
3(x-1)=2(x+1)+6
3x-3=2x+2+6
x=11


2006-11-16 14:16:31 補充：
第一條排位出錯4-5y=4y=0

2006-11-16 14:18:43 補充：
第4條做錯(2n-5)/3=(n-10)/93(2n-5)=n-106n-15=n-105n=5n=1

我會連問題一並打出來,好讓別人看得明白
1)6[2(2-y)-3y]=24
6(4-2y-3y)=24
4-5y=4
4-4=5y
5y=0
y=0
2)9(2a-1)=3[4(1+2a)-5]-8a
18a-9=3(4+8a-5)-8a
18a+8a=12+24a-15+9
26a-24a=6
2a=6
a=3
3)1/3(t+9)=1/3-0.5(t+3)
(先把0.5變為1/2,然後兩邊乘6)
1/3(t+9)=1/3-1/2(t+3)
6(1/3(t+9))=6(1/3)-6(1/2(t+3))
2(t+9)=2-3(t+3)
2t+18=2-3t-9
2t+3t= -7-18
5t= -25
t= -5
4)(2n-5)/3=(n-10)/9
(兩邊乘9)
9(2n-5)/3=9(n-10)/9
3(2n-5)=n-10
6n-n= -10+15
5n=5
n=1
5)(x-1)/2=(x+1)/3+1
(兩邊乘6)
6(x-1)/2=6(x+1)/3+6
3x-3=2x+2+6
3x-2x=8+3
x=11

1.
6 [ 2(2 - y) - 3y ] = 24
6(4 - 2y - 3y) = 24
6(4 - 5y) = 24
4 - 5y = 4 <------- Divided by 6 on both sides
5y = 0
y = 0

2.
9(2a - 1) = 3[4(1 + 2a) - 5] - 8a
18a - 9 = 3(4 + 8a - 5) - 8a
18a - 9 = 3(8a - 1) - 8a
18a - 9 = 24a - 3 - 8a
18a - 9 = 16a - 3
2a = 12
a = 6

3.
(t + 9) / 3 = 1/3 - 0.5(t + 3)
2(t + 9) / 6 = 2/6 - 3(t + 3)/6
2t + 18 = 2 - 3(t + 3)
2t + 18 = 2 - 3t - 9
2t + 18 = -7 - 3t
5t = -25
t = -5

4.
(2n - 5) / 3 = (n - 10) / 9
3(2n - 5) = n - 10 <----- Multiply by 9 on both sides
6n - 15 = n - 10
5n = 5
n = 1

5.
(x - 1) / 2 = (x + 1) / 3 + 1
3(x - 1) = 2(x + 1) + 6 <----- Multiply by 6 on both sides
3x - 3 = 2x + 2 + 6
x = 11

2006-11-16 14:20:58 補充：
Correct one: 2.9(2a - 1) = 3[4(1 + 2a) - 5] - 8a18a - 9 = 3(4 + 8a - 5) - 8a18a - 9 = 3(8a - 1) - 8a18a - 9 = 24a - 3 - 8a18a - 9 = 16a - 32a = 6a = 3