✔ 最佳答案
(3x+7) (x-1) = 4(x-1)
3x^2 + 4x - 7 = 4x -4
3x^2 - 3 = 0
x=1 or -1
2x^2-5x+3 用配方法@@
2(x^2 - 2.5x + 1.5)
=2[x^2 - 2.5x + (1.25)^2 - (1.25)^2 + 1.5]
=2(x-1.25)^2 -2(0.0625)
=2(x-1.25)^2 - 0.125
所以a= 2 , b= -1.25(-5/4) , c=0.125(1/8)
Amath來嫁咩= =?
2008-07-10 19:47:02 補充:
3x^2-11x-40 除 2x-1 = x-5
即( 2x-1 )( x-5) = 3x^2 -11x - 40
2x^2 -11x +5 = 3x^2 -11x - 40
x^2 -45 = 0
x=sqrt(45)
x=3sqrt(5)
2008-07-10 19:50:32 補充:
喂!你所講既答案,問題應該係
3x^2-11x-40 除 2x+1 = x-5
是 2x 加 1 ,不是2x 減 1
即
3x^2-11x-40 除 2x+1 = x-5
(2x+1)(x-5) = 3x^2-11x-40
2x^2 - 9x -5 = 3x^2-11x-40
x^2 -2x -35=0
(x-7)(x+5)
所以x=7 or -5
2008-07-10 19:51:30 補充:
\_/
想話就話人啦,做咩要加個令仔上去
最唔鍾意人咁講
2008-07-10 19:51:58 補充:
為左果10分仲要受你氣
2008-07-10 20:08:45 補充:
頭先我語氣也重了一些,對不起!