數學難題(快)

1. 2x-7+5x=8-12x
5X=(8+7)
X=3

2. 8x-12-12x=5x-25
-9x=-13
x=13/9

3. 7-2(x-3)=15-(x+3)
7-2X+3=15-X-3
-x=5
x=-5

4. 8(x-2)2(3x-1)=1
(8x-16)(6x-2)=1
48x^2-16x-96x+32-1=0
48x^2-112x+31=0
x= [-(-112)正負開方(-112)^2-(4)(48)(31)] over 2(48)
= (14正負開方103)over 12

2007-10-13 18:57:03 補充：
sorry ` 第1題錯左 `係. 2x-7+5x=8-12x 19X=(8+7) X=15/19呢個先岩.

1. 2x-7+5x=8-12x
5X=(8+7)
X=3

2. 8x-12-12x=5x-25
-9x=-13
x=13/9

3. 7-2(x-3)=15-(x+3)
7-2X+3=15-X-3
-x=5
x=-5

4. 8(x-2)2(3x-1)=1
(8x-16)(6x-2)=1
48x^2-16x-96x+32-1=0
48x^2-112x+31=0
x= [-(-112)正負開方(-112)^2-(4)(48)(31)] over 2(48)
= (14正負開方103)over 12

1) 2x-7+5x=8-12x
2x+5x+12x=8+7
19x=15
x=15/19

2) 8x-12-12x=5x-25
8x-12x-5x=-25+12
-9x=-13
x=13/9

3) 7-2(x-3)=15-(x+3)
7-2x+6=15-x-3
-2x+x=15-3-7-6
-x=-1
x=1

4) 8(x-2)2(3x-1)=1
(8x-16)(6x-2)=1
48x-16x-96x+32=1
48x-16x-96x=1-32
-64x=-31
x=31/64

1. 2x-7+5x=8-12x
2x+5x-12x=8+7
-5x =15
15
x= ─
-5
x=-3

2.8x-12-12x=5x-25
8x-12x-5x=-25+12
-9x=-13
-13
x = ─
-9
13
x = ─
9
3.7-2(x-3)=15-(x+3)
7-2x+6=15-x-3
-2x+x=15-3-7-6
-x=-1
x=1
4.8(x-2)2(3x-1)=1
8x-16+6x-2=1
8x+6x=1+16+2
14x=19
19
x= ─
14