Math (20點!!!)

你好～～～

以下都是敝人的一些愚見而已，如有錯誤請多多指教！

1) 2+[3分之2-(-7+4)]

= 2 + [2/3 - (-3)]

= 2 + (2/3 + 3)

= 5 + 2/3

= 5 又 2/3

2) -12+[10-(-8又4分之3)-25]-(2-6又4分之1)

= -12 + (10 + 35/4 - 25) - (2 - 25/4)

= -12 + (-25/4) - 2 + 25/4

= -12 - 2

= -14

3) A submarine moves 50 m up from 100 m below the sea level,and then moves 80 m down.Express the final location of the submarine in a directed number.

Sol: Original Distance = -100m

50m up = +50m

80m down = -80m

-100 + 50 - 80 m

= -130m

4) One day,Kevin forgot to bring his wallet.In the morning,he borrowed $12 from Vivian for breakfast.In the afternoon,he borrowed$22 from her again for lunch.If Kevin returnes$20 to Vivian the next day,how much was he still owing Vivian?

Sol: The first borrowing = -$12

The second borrowing = -$22

The return = +$20

$(-12 - 22 + 20) = $(-34 + 20) = -$14

5a) (2)(+6)

= 2 x 6

= 12

5b) (+10)(+15)

= 10 x 15

= 150

5c) (+7)(-9)

= 7 x (-9)

= -63

5d) (-5)(+20)

= 20 x (-5)

= -100

5E) (-8)(-6)

= (-1 x 8)(-1 x 6)

= (-1)(-1) x (8 x 6)

= 1 x 48

= 48

5f) (-3)(-12)

= (-1)^2 x (3 x 12)

= 1 x 36

= 36

6a) (+35)/(+5)

= 35 / 5

= 7

6b) (+48)/(-2)

= 48 / (-2)

= -24

6c) (-32)/(+8)

= -4

6d)(-24)/(-3)

= (-1)(24) / (-1)(3)

= 8

6e)-9分之+126

= (-9) / (+126)

= (-1) / 14

= -(1 / 14)

6f) -11分之-242

= (-11) / (-242)

= (-1)(11) / (-1)(242)

= 1 / 22

要記得︰

(-)(+) = -

(+)(-) = -

(+)(+) = +

(-)(-) = +

(+) / (-) = -

(-) / (+) = -

(+) / (+) = +

(-) / (-) = +

希望可以幫到你～～～～～

2010-09-14 20:17:15 補充：
這位抄襲者真醒目，幸好他是小學級三級，才能轉顏色呢～～～～～

1) 2+[3分之2-(-7+4)]
= 2 + [2/3 - (-3)]
= 2 + (2/3 + 3)
= 5 + 2/3
= 5 又 2/3

2) -12+[10-(-8又4分之3)-25]-(2-6又4分之1)
= -12 + (10 + 35/4 - 25) - (2 - 25/4)
= -12 + (-25/4) - 2 + 25/4
= -12 - 2
= -14

3) A submarine moves 50 m up from 100 m below the sea level,and then moves 80 m down.Express the final location of the submarine in a directed number.

Sol: Original Distance = -100m

50m up = +50m

80m down = -80m

-100 + 50 - 80 m
= -130m

4) One day,Kevin forgot to bring his wallet.In the morning,he borrowed $12 from Vivian for breakfast.In the afternoon,he borrowed$22 from her again for lunch.If Kevin returnes$20 to Vivian the next day,how much was he still owing Vivian?

Sol: The first borrowing = -$12

The second borrowing = -$22

The return = +$20

$(-12 - 22 + 20) = $(-34 + 20) = -$14

5a) (2)(+6)
= 2 x 6
= 12

5b) (+10)(+15)
= 10 x 15
= 150

5c) (+7)(-9)
= 7 x (-9)
= -63

5d) (-5)(+20)
= 20 x (-5)
= -100

5E) (-8)(-6)
= (-1 x 8)(-1 x 6)
= (-1)(-1) x (8 x 6)
= 1 x 48
= 48

5f) (-3)(-12)
= (-1)^2 x (3 x 12)
= 1 x 36
= 36

6a) (+35)/(+5)
= 35 / 5
= 7

6b) (+48)/(-2)
= 48 / (-2)
= -24

6c) (-32)/(+8)
=-4

6d)(-24)/(-3)
= (-1)(24) / (-1)(3)
= 8

6e)-9分之+126
= (-9) / (+126)
= (-1) / 14
= -(1 / 14)

6f) -11分之-242
= (-11) / (-242)
= (-1)(11) / (-1)(242)
= 1 / 22

P.S.

(-)(+) = -

(+)(-) = -

(+)(+) = +

(-)(-) = +

(+) / (-) = -

(-) / (+) = -

(+) / (+) = +

(-) / (-) = +

希望幫到你 :P