各位知識朋友 , 入黎幫我手 ar !!! ( 數學F.1 ) (2)

1.(a) (+2)+(-3)+(-1)

2-3-1

is -2

(b) (-5)+(-3)+(-1)

-5-3-1

is -9

(c) (-2)-(-3)-(+4)

-2+3-4

is -3

(d) (+5)-(-4)-(-3)

5+4+3

is 12

幫唔幫到你?

1a) (+2)+(-3)+(-1)
=2-3-1
=-2
b) (-5)+(-3)+(-1)
=-5-3-1
=-9
c) (-2)-(-3)-(+4)
=-2+3-4
=-3
(d) (+5)-(-4)-(-3)
=5+4+3
=12

原因: 1)正正得正 ,, 正負得負 ,, 負負得正 (+ =正;- =負)
即系+(+2)=2 ,, +(-3)=-3 ,, -(-2) =2

你可以用計數機試下嫁,,

1.(a)
(+2)+(-3)+(-1)
=2-3-1
=-1-1
=-2
(b)
(-5)+(-3)+(-1)
=-5-3-1
=-8-1
=-9
(c)
(-2)-(-3)-(+4)
=-2+3-4
=1-4
=-3
(d)
(+5)-(-4)-(-3)
=5+4+3
=9+3
=12

(a) (+2)+(-3)+(-1)
= 2-3-1
= -2
(b) (-5)+(-3)+(-1)
= -5-3-1
= -9
(c) (-2)-(-3)-(+4)
= -2+3-4
= -3
(d) (+5)-(-4)-(-3)
= 5+4+3
= 12

1.(a)(+2)+(-3)+(-1)
=+2-3-1
=+2-4
=-2
1.(b)(-5)+(-3)+(-1)
= -5-3-1
= -9
1.(c)(-2)-(-3)-(+4)
= -2+3-4
= -2-1
= -3
1.(d)(+5)-(-4)-(-3)
= +5+4+3
= +12

如喜歡,可省略步驟!=]

a)(+2)+(-3)+(-1)=+2-3-1=-2
b)(-5)+(-3)+(-1)=-5-3-1=-9
(c)(-2)-(-3)-(+4)=-2+3-4=-3
(d)(+5)-(-4)-(-3)=+5+4+3=12
正正得正 +(+3)
負負得正 -(-3)
正負或負正得負+(-1)