中四二元一次 (急需)

我用(^2) = 二次方

1) 10x^2+x-3=0
(2x-1)(5x+3)=0
2x-1=0 / 5x+3=0
x=2分之1 / x=5分之-3

2) 5x^2+39x+28=0
(5x+4)(x+7)=0
5x+4=0 / x+7=0
x=5分之-4 / x=-7

3) 7x^2+20x-3=0
(7x-1)(x+3)=0
7x-1=0 / x+3=0
x=7分之1 / x=-3

4) 5x^2+9x+4=0
(5x+2)(x+2)=0
5x+2=0 / x+2=0
x=5分之-2 / x=-2

5) x^2-x-6=0
(x-3)(x+2)=0
x-3=0 / x+2=0
x=3 / x=-2

6) x^2+2x-8=0
(x+4)(x-2)=0
x+4=0 / x-2=0
x=-4 / x=2

2008-09-07 20:09:34 補充：
第4條打錯左

係應該:

5x^2+9x+4=0

(5x+4)(x+1)=0

5x+4=0 / x+1=0

x=5分之-4 / x=-1

1. (5x+3)(2x-1)=0
5x+3=0 or 2x-1=0
x=-3/5 or x=-1/2

2. (5x+4)(x+7)=0
5x+4=0 or x+7=0
x=-4/5 or x=-7

3. (7x-1)(x+3)=0
7x-1=0 or x+3=0
x=-1/7 x=-3

4. (5x+4)(x+1)=0
5x+4=0 or x+1=0
x=-4/5 or x=-1

5. (x+2)(x-3)=0
x+2=0 or x-3=0
x=-2 or x=3

6. (x+4)(x-2)=0
x+4=0 or x-2=0
x=-4 or x=2