小六數學問題一問(20分)

正負數：

當A=(-2)，B=3和c=(-1)時，求下例各代數式的值

(A) abc

=(-2)x(3)x(-1)
= 6

解釋：
正負數乘除 首先計左數字 吾好理d正負號先 等如 2 x3 x 1=6
之後就計正負號 條式 (-2)x(+3) =(-)x(+) = 負正得負 = -6
(-6)x(-1) = 負負得正 = +6 / 6

(B) -a-(-b)+c

= -(-2)-(-3)+(-1)
= 2+3-1
=4

解釋：
-(-2) = 將出面個負號乘去入面個負號 = 負負得正 =+2
-(-3) = 將出面個負號乘去入面個負號 = 負負得正 =+3
+(-1)= 將出面個正號乘去入面個負號 = 正負得負 = -1

(C) 2a-b-c

= 2x (-2) -3-(-1)
= -4 -3+1
=-6

解釋：

2X(-2) = 正2 x 負2 = 正負得負 = -4
-(-1) = 將出面個負號乘以入要個負號 = 負負得正 = +1


(D)a+b
——
c
= (-2)+3
_____
-1

= -2+3
____
-1

= +1
__
-1

= -1

解釋：
(-2)+3 = 刪括號 = -2+3 = +1

+1
___ = 正負得負 = -1
-1

(A)

abc

= (-2) x 3 x (-1)

= 6



(B)

-a-(-b)+c

= -(-2) - (-3) + (-1)

= 2 + 3 - 1

= 4



(C)

2(-2)-3+1

= -6


(D) -2+3

=1

(A) abc = (-2)(3)(-1) = 6

(B) -a-(-b)+c = -(-2)-(-3)+(-1) = 2+3-1= 4

(C) 2a-b-c = 2(-2)-3-(-1) = -4-3+1 = -6

(D) (a+b)/c = (-2+3)/-1 = -1

記住負負得正，正負得負就好易做架啦~~

例: -(-1) = +1、1/-1=-1、-1/-1=+1、+(-1)=-1、-(+1)=-1

希望幫到你 ^.^

(A)
abc
= (-2) x 3 x (-1)
= 6

(B)
-a-(-b)+c
= -(-2) - (-3) + (-1)
= 2 + 3 - 1
= 4

(C)
(a + b) / c
= (-2 + 3) / (-1)
= 1 / (-1)
= -1