equation

x=a+1

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choose me plz!!
thx!!

2007-10-29 17:51:36 補充：
sorry,is a-1!!

2007-10-29 18:00:34 補充：
equation:(x-4)(x 5)=(a 4)(a-5)x^2 5x-4x-20= a^2-5a 4a-20x^2 x= a^2-ayou need to guess now:x=3 a=43^2 3= 4^2 412= 12it works!!!after a few guessesyou will get:x= a-1

2007-10-29 18:01:40 補充：
請支持我

(x-4)(x+5) = (a+4)(a-5)

x^2 - 4x + 5x - 20 = a^2 + 4a - 5a - 20
x^2 + x = a^2 - a
x^2 - a^2 + x + a = 0
(x+a)(x-a) + (x+a) = 0
(x+a) [(x-a)+1] = 0
x+a = 0 or x-a+1 = 0
x = -a or x = a-1

雖然有點不禮貌
但樓上面位忘了二次方程應該有兩個根才對
請支持我

(x-4)(x+5)=(a+4)(a-5)
=> (x-4)(x+5)=[-(-a-4)][-(-a+5)]
=> (x-4)(x+5)=(-a-4)(-a+5)
=> x = -a