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标题: [求助]GG10的第15题不会做,大家帮帮我 [打印本页]

作者: audiencer    时间: 2009-1-13 13:40     标题: [求助]GG10的第15题不会做,大家帮帮我

题目:Which of the following equations has a root in common with X2– 6X + 5 = 0?

(A) X2 + 1 = 0

(B) X2x – 2 =0

(C) X2– 10x – 5 =0

(D) 2 X2– 2 =0

(E) X2– 2x – 3 =0

解释:

Since X2 – 6X + 5 = (X - 5)(X- 1), the roots

of X2– 6X + 5 = 0 are 1 and 5. when

these two values are substituted in each

of the five choices to determine

whether or not they satisfy the equation,

only in D does a value satisfy the

equation, namely, 2(1) 2 – 2 = 0. So, D

is the correct answer.

看完解释,还是不明白X2 – 6X + 5 为什么会等于 (X - 5)(X- 1)阿?各位牛牛帮帮我

Since X2 – 6X + 5 = (X - 5)(X- 1), the roots

of X2– 6X + 5 = 0 are 1 and 5. when

these two values are substituted in each

of the five choices to determine

whether or not they satisfy the equation,

only in D does a value satisfy the

equation, namely, 2(1) 2 – 2 = 0. So, D

is the correct answer.

看完解释,还是不明白X2 – 6X + 5 为什么会等于 (X - 5)(X- 1)阿?各位牛牛帮帮我


作者: AlphaBeta    时间: 2009-1-13 19:46

这个是最简单的因式分解啊。。。

这个最好去看看教材吧。。。


作者: audiencer    时间: 2009-1-14 19:37

这是题目:Which of the following equations has a root in common with X2– 6X + 5 = 0?

可是题目中没给出任何条件是X2– 6X + 5 = (X-1)(X-5)。

题目遗漏了


作者: renprincer    时间: 2009-1-15 07:34

不是遗漏了,通过X2– 6X + 5 =0推出 (X-1)(X-5)=0,这是数学上最基本的因式分解,自己可以推出的




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