1.which of the following is/are true?
(I) (a-b)(a-b) = (b-a)(b-a)
(II) (-a-b)(-a-b) = (a+b)(a+b)
(III) (-a+b)(-a+b) = (a-b)(a-b)
A. (II) only
B. (I) and (II) only
C. (II) and (III)
D. all of the above
Form 2 Mathematics
2007-01-05 4:32 am
回答 (4)
2007-01-05 4:59 am
✔ 最佳答案
答案係D我唔記得中二學左take out common factor未(記憶中好似有)
l (a-b) (a-b) = (b-a) (b-a)
(a-b) (a-b) = -1(-b+a) x (-1) (-b+a)
(a-b) (a-b) = (a-b) (a-b) 成立
因為-1 x -1 = 1(負負得正)
ll (-a-b) (-a-b) = (a+b) (a+b)
-1(a+b) x (-1) (a+b) = (a+b) (a+b)
(a+b) (a+b) = (a+b) (a+b) 成立
lll (-a+b) (-a+b) = (a-b) (a-b)
-1(a-b) x (-1) (a-b) = (a-b) (a-b)
(a-b) (a-b) = (a-b) (a-b) 成立
因為 l ll lll 都成立 ,所以答案係D
參考: 自己
2007-01-05 4:44 am
if a=3,b=2
(I)(3-2)(3-2)=(2-3)(2-3).........false
(II)(-3-2)(-3-2)=(3+2)(3+2).......true
(III)(-3+2)(-3+2)=(3-2)(3-2).........true
therefore ,answer is C
(I)(3-2)(3-2)=(2-3)(2-3).........false
(II)(-3-2)(-3-2)=(3+2)(3+2).......true
(III)(-3+2)(-3+2)=(3-2)(3-2).........true
therefore ,answer is C
2007-01-05 4:37 am
d
(a-b)(a-b)=(b-a)(b-a)
a*a+b*b-2ab=a*a+b*b-2ab
(a-b)(a-b)=(b-a)(b-a)
a*a+b*b-2ab=a*a+b*b-2ab
2007-01-05 4:35 am
C is true
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