Math (20點!!!)

你好～～～

以下都是敝人的一些意見，如有錯誤請多多指教～～

1. (+14)(-3)-(-56)/(+7)

= (-42) - (-8)

= (-42) + 8

= -34

2. [(-16)-(-8)]/[(+14)-(-18)]

= (-16 + 8) / (14 + 18)

= (-8) / 32

= -(1 / 4)

3. [7-(-3)]-(-8)

= (7 + 3) + 8

= 18

4. 4-(6-12)

= 4 - (-6)

= 4 + 6

= 10

5. (-5)+[10-(-9)]

= (-5) + (10 + 9)

= 19 - 5

= 14

6. [(-3)+(-5)-(-4)]-(-3)

= [(-3) + (-5) + 4] + 3

= -3 - 5 + 4 + 3

= -1

7. (+2)+(-4.5)-(-6.5)

= 2 - 4.5 + 6.5

= 4

8.a diver first dived into a position of 20 m below sea level,then moved up 10 m,and finally dived 60 m downwards.express the final location of the diver in positive or negative number.

Sol:

First, the diver dived into 20m below = -20m

moved up 10m = + 10m

dived 60m downwards = -60m

The final location = -20 + 10 - 60 m = -70m

9.ken went 6 floors up by a lift from basement 3 and then went 4 floors down.which floor did he reach?

Sol: Original floor = -3(basement means 地下室)

Went 6 floors up = +6

Went 4 floors down = -4

The floor he reached = -3 + 6 - 4 = -1

10.the temperature of city a was -3。c yesterday morning.

a. if the temperature of city b was 2。c lower than that of city a yesterday morning,find the temperature of city b yesterday morning.

Sol:

Original temperature : -3。C

2。C lower than that of city a yesterday morning = -2。C

Yesterday morning's temperture = -3 -+ 2 。C = -5。C

b. at noon yesterday,the temperature of city b went up by 10。c.if the temperature of the two cities were the same at that time,find the temperature of city a at noon yesterday.

Sol:

The city b's temperature in the morning yesterday = -5。C

Went up by 10。C = +10。C

The temperature of city a is equal to that of city b = -5。C + 10。C = 5。C

c. in the evening,the temperature of city b was -8。c.to compare with the temperature in the morning,what is the change in temperature ?

The temperature in the morning = -5。C

The temperature in the evening = -8。C

The change in temperature = -8 - (-5) 。C = -8 + 5 。C = -3。C

希望以上答案可以幫到你～～～～～

1.(+14)(-3)-(-56)/7
=42-(-8)
=42+8
=50,,
2. [(-16)-(-8)]/[(+14)-(-18)]
=(-16+8)/(+14+18)
=(-8)/32
=1.1875 or 19/16
3. [7-(-3)]-(-8)
=(7+3)+8
=10+8
=18
4. 4-(6-12)
=4-(-6)
=4+6
=10
5. (-5)+[10-(-9)]
=(-5)+(10+9)
=(-5)+19
=14
6. [(-3)+(-5)-(-4)]-(-3)
=(-3-5+4)+3
=-4+3
=-1
7. (+2)+(-4.5)-(-6.5)
=2-4.5+6.5
4