好難的方程

1.
3 - x = 7 - 3x
3x - x = 7 -3
2x = 4
x = 2

2.
2(2y + 1) = 6y
4y + 2 = 6y
2 = 6y - 4y
2 = 2y
y = 1

3.
2x - (3 - x) = 2 + 4x
2x - 3 + x = 2 + 4x
3x - 3 = 4x + 2
-3 - 2 = 4x - 3x
-5 = x

4.
5(2a - 5) + 4(1 - a) = 3
10a - 25 + 4 - 4a = 3
6a - 21 = 3
6a = 24
a = 4

5.
4(x - 1) = 3(x + 3) + 2
4x - 4 = 3x + 9 + 2
4x - 3x = 9 + 2 + 4
x = 15

6.
10y = -9(3 - y)
10y = -27 + 9y
10y - 9y = -27
y = -27

首先你要知道計法,是先分別把等號左邊及右邊分別計的計算好,
然後把相同的單位於在同一邊,但在對掉時打原本是正的放在另一邊是變為負
原本是負的放在另一邊變為正,同樣乘變為除,除變為乘.小心對掉就不太難.

1. 3 - x = 7 - 3x
3x - x = 7 -3
2x = 4
x = 2

2. 2(2y + 1) = 6y
4y + 2 = 6y
2 = 6y - 4y
2 = 2y
y = 1

3. 2x - (3 - x) = 2 + 4x
2x - 3 + x = 2 + 4x
3x - 3 = 4x + 2
-3 - 2 = 4x - 3x
-5 = x

4. 5(2a - 5) + 4(1 - a) = 3
10a - 25 + 4 - 4a = 3
6a - 21 = 3
6a = 24
a = 4

5. 4(x - 1) = 3(x + 3) + 2
4x - 4 = 3x + 9 + 2
4x - 3x = 9 + 2 + 4
x = 15

6. 10y = -9(3 - y)
10y = -27 + 9y
10y - 9y = -27
y = -27

3-x=7-3x
3-7=x-3x
-4=-2x
x=2
-----------------------
2(2y+1)=6y
4y+2=6y
4y-6y=-2
-2y=-2
y=1
------------------------
2x-(3-x)=2+4x
2x-3+x=2+4x
3x-4x=2+3
-x=5
x=-5
------------------------------
5(2a-5)+4(1-a)=3
10a-25+4-4a=3
6a=24
a=6
-------------------------------
4(x-1)=3(x+3)+2
4x-4=3x+9+2
4x-3x=11+4
x=15
------------------------------
10y=-9(3-y)
10y=-27+9y
y=-27

2010-01-02 15:46:03 補充：
5(2a-5)+4(1-a)=3
10a-25+4-4a=3
6a=24
a=4 投先打錯

1
3-x=7-3x
3x-x=7-3
2x=4
x=2

2
2(2y+1)=6y
4y+2=6y
2=2y
y=1

3
2x-(3-x)=2+4x
2x-3+x=2+4x
-3-2=4X-3x
x=-5

4
5(2a-5)+4(1-a)=3
10a-25+4-4a=3
6a=3-4+25
a=24/6=4

5
4(x-1)=3(x+3)+2
4x-4=3x+9+2
x=11+4=15

6
10y=-9(3-y)
10y=-27+9y
y=-27