[求助]GG10的第15题不会做，大家帮帮我

audiencer

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

(A) X² + 1 = 0

(B) X²– x – 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

AlphaBeta

这个是最简单的因式分解啊。。。

这个最好去看看教材吧。。。

audiencer

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

renprincer

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