章节大纲

  • lesson content

    Matt is making a dress for his sister. He has  7 2 3  yards of fabric. He needs  2 1 3   yards to make the dress. How much fabric will Matt have after he makes her dress?
    ::马特为妹妹做衣服 他有723码的布料 他需要23码的布料

    In this concept, you will learn how to subtract mixed numbers. 
    ::在这个概念中,你会学会如何减去混合数字。

    Subtracting Mixed Numbers without Renaming
    ::不重命名的混合数字减法

    mixed number  is a whole number with a fraction. Just as you can add mixed numbers, you can also subtract mixed numbers in the same way. Subtract the fractions first and then the  whole numbers .
    ::混合数字是一个包含一个分数的整数。正如您可以添加混合数字一样,您也可以以同样的方式减去混合数字。先减去分数,然后减去整数。

    Here is a subtraction problem. 
    ::这是一个减法问题。

        6 3 8       4 1 8 _

    Start by subtracting the fractions. These fractions have the same  denominator  so you can simply subtract the numerators. 
    ::以减去分数开始。这些分数具有相同的分母,这样您就可以简单地减去分子。

        6 3 8       4 1 8 _         2 8

    Next, subtract the whole numbers.
    ::接下来,减去全部数字。

        6 3 8       4 1 8 _     2 2 8

    Finally,  simplify  the fraction in   2 2 8
    ::最后,将分数简化为 2 2 8 。

    2 2 8 = 2 1 4

    The final answer is  2 1 4 .
    ::最后一个答案是2 14。

    If the subtraction problem involves mixed numbers with different denominators, rewrite the fractions of the mixed numbers so they have a  common denominator  before subtracting.
    ::如果减法问题涉及具有不同分母的混合数字,请重写混合数字的分数,以便在减法前有一个共同分母。

    Here is another subtraction problem. 
    ::这是另一个减法问题。

        6 3 4       3 1 6 _

    First, rewrite the fractions with a common denominator. The common denominator is 12. 
    ::首先,用共同分母重写分母。 共同分母为 12 。

    3 4 = 9 12 1 6 = 2 12

        6 9 12       3 2 12 _

    Then, subtract the fractions. 
    ::然后,扣除分数。

        6 9 12       3 2 12 _         7 12
     Next, subtract the whole numbers. 

        6 9 12       3 2 12 _     3 7 12

    The  difference  is  3 7 12 .
    ::差数是3 7 12

    Examples
    ::实例

    Example 1
    ::例1

    Earlier, you were given a problem about Matt making a dress for his sister.
    ::之前有人给你一个问题 马特为他妹妹做衣服

    Matt has  7 2 3  yards of fabric and uses  2 1 3   yards to make his sister a dress. Subtract the  amount  of fabric he used from the original amount to find how much fabric he has left. 
    ::马特有7,2,3码的布料,用2,13码的布料 给他妹妹做一件衣服。减去他用在原来数量的布料 来找出他剩下多少布料。

      7 2 3 2 1 3 = _

    First, subtract the fractions.
    ::首先,减去分数。

      2 3 1 3 = 1 3

    Then, subtract the whole numbers.
    ::然后,减去全部数字。

      7 2 = 5 7 2 3 2 1 3 = 5 1 3

    Matt will have  5 1 3  yards of fabric left over. 
    ::马特还有513码的布料

    Example 2
    ::例2

    Subtract the fractions. Answer in  simplest form .
    ::减去分数。 回答最简单。

    12 46 49 10 39 49 = _

    The fractions have a common denominator.
    ::分数有一个共同的分母。

    First, subtract the fractions. 
    ::首先,减去分数。

     

    46 49 39 49 = 7 49

    Then, subtract the whole numbers.
    ::然后,减去全部数字。

     

    12 10 = 2 12 46 49 10 39 49 = 2 7 49

    Next, simplify the fraction part of the mixed number.
    ::接下来,简化混合数字的分数部分。

    2 7 49 = 2 1 7

    The difference is  2 1 7 .
    ::差数是2 17

    Example 3
    ::例3

    Subtract the fractions:  4 4 5 3 1 5 = _ . Answer in simplest form.
    ::减去分数: 4 4 5 - 3 1 5 = _. 回答最简单。

    First, subtract the fractions.
    ::首先,减去分数。

     

    4 5 1 5 = 3 5

    Then, subtract the whole numbers.
    ::然后,减去全部数字。

    4 3 = 1 4 4 5 3 1 5 = 1 3 5

    The difference is  1 3 5 .
    ::差别是13 5。

    Example 4
    ::例4

    Subtract the fractions:  6 4 6 1 2 6 = _ . Answer in simplest form.
    ::减去分数: 6 4 6 - 1 2 6 = _. 回答最简单。

    First, subtract the fractions.
    ::首先,减去分数。

     

    4 6 2 6 = 2 6

    Then, subtract the whole numbers.
    ::然后,减去全部数字。

     
    6 1 = 5 6 4 6 1 2 6 = 5 2 6

    Next, simplify the fraction part of the mixed number.
    ::接下来,简化混合数字的分数部分。

     

    5 2 6 = 5 1 3

    The difference is  5 1 3 .
    ::差别是513

    Example 5
    ::例5

    Subtract the fractions:  7 8 9 4 4 6 = _ . Answer in simplest form.
    ::减去分数: 7 8 9 - 4 4 6 = _. 回答最简单。

    First, rewrite the fractions with a common denominator of 18. 
    ::首先,重写分数,共同分母为18。

     

    8 9 = 16 18 4 6 = 12 18 7 16 18 4 12 18 = _

    Then, subtract the fractions.
    ::然后,扣除分数。

     

    16 18 12 18 = 4 18

    Next, subtract the whole numbers.
    ::接下来,减去全部数字。

     
    7 4 = 3 7 16 18 4 12 18 = 3 4 18
    Finally, simplify the fraction.
     
    3 4 18 = 3 2 9

    The difference is  3 2 9 .

    ::差别是3 2 9

    Review
    ::回顾

    Subtract the following mixed numbers. Answer in simplest form.
    ::减去下列混合数字。回答最简单。

    1. 6 2 9 4 1 9 = _
    2. 5 6 10 2 1 10 = _
    3. 8 2 8 4 1 8 = _
    4. 12 4 8 4 2 8 = _
    5. 6 9 10 4 2 10 = _
    6. 15 6 15 5 3 15 = _
    7. 18 4 12 7 2 12 = _
    8. 20 5 20 19 1 20 = _
    9. 5 2 5 1 1 3 = _
    10. 8 1 2 4 1 4 = _
    11. 6 1 3 2 1 6 = _
    12. 5 1 4 3 2 10 = _
    13. 8 1 3 2 1 4 = _
    14. 12 3 4 2 1 3 = _
    15. 18 6 9 12 1 4 = _

    Review (Answers) 
    ::回顾(答复)

    Click   to see the answer key or go to the Table of Contents and click on the Answer Key under the 'Other Versions' option.
    ::单击可查看答题键, 或转到目录中, 单击“ 其他版本” 选项下的答题键 。

    Resources
    ::资源