2.4 减去整数和其他合理数字-interactive

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  减法整数和其他有理数字

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  Subtracting Integers
  ::减减整数

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  Subtraction is defined as taking away a value from another. As you saw in the previous lessons, adding a negative number is subtraction. On a number line , adding an integer meant moving units in the direction of the sign of that number. So, adding -4 would mean moving 4 units to the left.  With subtraction, it is the opposite. Subtracting -4 would mean moving 4 units to the right . Therefore, subtraction can also be defined as adding the opposite .  
  ::减法的定义是从另一个数值中取走一个数值。正如您在前一课中看到的那样,增加一个负数是减法。在数字行中,增加一个整数意味着向数字符号的方向移动单位。因此,增加 -4意味着向左移动4个单位。减法则相反。减法 - 4意味着向右移动4个单位。因此,减法也可以定义为向相反的添加。

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  $$\begin{array}{r}2-(-4)=2+4\end{array}$$

  When doing subtraction problems, change the problem to adding the opposite before starting. 
  ::2 - (-4) = 2+4 当做减法问题时, 将问题改为在开始之前加上相反。

   

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  Diving Depths
  ::潜水深度

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  Fatima is learning how to scuba dive. She is experimenting with different depths as she swims in the ocean. If zero is the surface of the water, she starts 5 feet below that and then dives another 12 feet further. How far below the surface is she?
  ::法蒂玛正在学习如何潜水。 当她在海洋中游泳时,她正在以不同的深度进行实验。如果水面为零,她就会在水面下开始5英尺,然后再进一步下潜12英尺。她在地表下方有多远?

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  Use the diver and the number line in the interactive to help you determine the answer.
  ::使用互动中的潜水器和数字行来帮助您确定答案。

   

   

   

   

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  When subtracting integers, remember to add the opposite.  To help you organize subtraction with the different cases, see the table below.
  ::减去整数时,请记住要加上相反的值。要帮助您组织不同大小写中的减法,请见下表。

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  $$\begin{array}{r}\begin{array}{|cc|}\hline \mathbf{\text{Case}}& \mathbf{\text{Example}}\\ & 9-3\\ \text{[positive] }-\text{[positive]}& 9+(\text{-}3)\\ & 6\\ & 8-(-5)\\ \text{[positive] }-\text{[negative]}& 8+5\\ & 13\\ & -6-4\\ \text{[negative] }-\text{[positive]}& -6+(-4)\\ & -10\\ & -7-(-2)\\ \text{[negative] }-\text{[negative]}& -7+2\\ & -5\\ \hline\end{array}\end{array}$$

  
  ::案例9-3[正]-[正]-[正]9+9(3)68-(5)[正]-[正]8+513-6-4[负]-[正]6-6+(4)-10-7-(2)-(2)-[负]-[负]-7+2-5

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  When subtracting , the process will be the same as integers. 
  ::减去时,该流程将与整数相同。

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  Discussion Question
  ::讨论问题

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  Why is subtracting a negative integer the same as adding a positive integer?
  ::为什么减去负整数与加上正整数相同?

   

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  Banking
  ::银行银行银行

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  Gina has a savings account with $23.64 in it. She makes a withdrawal of $15.67 and then a deposit of $6.78. How much money is in her account?
  ::吉娜有一个存有23.64美元的储蓄账户 她提款了15.67美元 然后存款了6.78美元

   

   

   

   

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  You may use the interactive below to brush up on subtracting decimals:
  ::您可以使用下面的交互数据来刷新减去小数数的减法:

   

   

    

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  Burnt Bread
  ::烧烤面包

   

   

   

   

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     Summary
  ::摘要

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  • When subtracting integers, fractions, or decimals, always change the problem to adding the opposite of the second number. Then, approach like addition.
    ::当减去整数、分数或小数点时,总是会将问题改为与第二个数字相反的。然后,处理类似添加。
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  • When adding, if the signs of the numbers are the same, add the values and then give the answer the same sign as the numbers you added.
    ::添加时,如果数字的符号相同,请添加数值,然后给出与您添加的数字相同的符号。
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  • When adding, if the signs of the numbers are different, subtract the values, and then give the answer the sign of the larger number.
    ::添加时,如果数字的符号不同,请减去数值,然后给答案较大数字的符号。