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 | 
