跟读练习: Adding Fractions With Unlike Denominators - 通过视频学习英语口语

正在创建课程...
1
In this video, we're going to talk about how to add two fractions.
2
So let's start with this example.
3
2 over 3 plus 3 over 4.
4
So how can we add these two fractions?
5
The first thing you can do is multiply the denominators of the fractions.
6
3 times 4 is 12. And then cross multiply.
7
2 times 4 is 8, and then multiply 3 times 3, and that will give you 9.
8
And then you could add 8 and 9.
9
8 plus 9 is 17.
10
So we get the answer 17 over 12.
11
And so this is our answer as an improper fraction.
12
Now, let's try another example.
13
So let's add 5 over 3 plus 1 over 2.
14
So let's follow the same technique.
15
3 times 2 is 6. And then cross multiply.
16
5 times 2 is 10.
17
3 times 1 is 3.
18
And then we're going to add 10 plus 3.
19
So 10 plus 3 is 13.
20
So the answer is 13 over 6. by the way
21
if you want more videos on fractions let's say how to subtract fractions how to multiply
22
or divide fractions check out the description section of this video i'm going to post some links there
23
that you might find useful
24
but now let's get back to this video let's work on another problem
25
so now it's your turn go ahead and add the following fractions 2 over 5 plus 1 over 4
26
And also try this example, 3 over 7 plus 5 over 9.
27
Feel free to pause the video and try those examples.
28
So let's start with the first one.
29
So first we're going to multiply 5 and 4.
30
5 times 4 is 20. And then cross multiply.
31
2 times 4 is 8.
32
5 times 1 is 5.
33
And now we can add 8 plus 5 is 13.
34
So the answer is 13 over 20.
35
Now let's try the example below.
36
So let's multiply 7 by 9.
37
7 times 9 is 63. And then cross multiply.
38
3 times 9 is 27.
39
And 7 times 5 is 35.
40
So now we'll need to add 27 and 35.
41
So you can use a calculator or you can do it the old-fashioned way.
42
Let's do it the old-fashioned way.
43
5 plus 7 is 12, so we need to write the 2, carry over the 1.
44
And then 3 plus 2 plus 1 is 6.
45
So 27 plus 35 is 62.
46
So the final answer for that example is 62 divided by 63.
47
So at this point, you know how to add 2 fractions.
48
But what if you need to add, let's say, 3 fractions?
49
What should you do?
50
So before we go into this example, I want to show you another example of adding 2 fractions but using a different method.
51
So let's start with this problem, 3 over 8 plus 5 over 7.
52
So let's begin by using the method that you're familiar with
53
and then we'll use a new method to get the same answer.
54
So what we did before is multiply the two denominators of the fractions.
55
8 times 7 is 56.
56
And then we would cross multiply.
57
3 times 7 is 21.
58
And 8 times 5 is 40.
59
And then we would add 21 plus 40 is 61.
60
So our answer for this example would be 61 over 56.
61
Now here's another method which is useful if you're adding multiple fractions.
62
So what you want to do is get a common denominator of 56.
63
In order to do so, the fraction on the left you need to multiply the top and the bottom by 7.
64
And for the fraction on the right, multiply the top and the bottom by 8.
65
So this would give you a common denominator of 56.
66
So 3 times 7 is 21, and 7 times 8 is 56.
67
5 times 8 is 40, and on the bottom, 7 times 8 is 56.
68
Now whenever you're adding two fractions, if the denominator is the same, then you're allowed to add the numerators of the two fractions.
69
So 21 plus 40 is 61.
70
And thus, we're going to get the same answer of 61 over 56.
71
This technique works if you're adding, let's say, three fractions or even four fractions.
72
Now, let's try this example.
73
2 over 5 plus 3 over 4 plus 1 over 3.
74
So the first thing we need to do is identify a common denominator that we need to get to.
75
So we need to find the least common multiple of 5, 4, and 3.
76
How can we do so?
77
Well, a simple way is to multiply 5 times 4 times 3.
78
You could use any common multiple.
79
It doesn't really have to be the least common multiple.
80
But if you could find the least common multiple, then it's going to be easier.
81
But let's keep it simple.
82
so 5 times 4 times 3
83
5 times 4 is 20 20 times 3 is 60 so 60 is a common multiple of 5, 4, and 3 it might even be the least common multiple
84
and I think it is so what I'm going to do now is take 60 and divide it by 5
85
60 divided by 5 is 12 so therefore I'm going to multiply the second fraction, I mean the first fraction, by 12.
86
So that will give me a common denominator of 60.
87
Now 60 divided by 4 is 15.
88
So I need to multiply the second fraction, the top and the bottom, by 15.
89
Whatever you multiply the bottom of a fraction by, you need to do so also to the top.
90
Now 60 divided by 3 is 20.
91
So I'm going to multiply the third fraction by 20 over 20.
92
12 times 2 is 24 and we know that 12 times 5 is 60.
93
15 times 3 is 45 and 15 times 4 is 60.
94
20 times 1 is 20.
95
20 times 3 is 60.
96
So notice that we have a common denominator of 60.
97
So now all we need to do is add up the three numerators.
98
So let's find a sum of 45, 24, and 20.
99
5 plus 4 is 9.
100
4 plus 2 plus 2 is 8.
101
So 24 plus 45 plus 20 is 89.
102
So our answer for this problem is 89 over 60.
103
So that's how you can add three fractions together.
104
Now let's try another example.
105
So now it's your turn.
106
Go ahead and add 1 over 4 plus 5 over 6 plus 1 over 2.
107
So let's identify the least common multiple of 4, 6, and 2.
108
Multiples of 6 are 6, 12, 18, 24, and so forth.
109
Multiples of 4 are 4, 8, 12, 16, 20.
110
Multiples of 2 are 2, 4, 6, 8, 10, 12, 14.
111
So which of these are the least common multiple of 2, 4, and 6?
112
Notice that 12 is the lowest common number or lowest common multiple of 2, 4, and 6.
113
So therefore, 12 is the least common multiple.
114
Now, 12 divided by 4 is 3.
115
So I'm going to multiply this fraction by 3 over 3.
116
And 12 divided by 6 is 2.
117
So I'm going to multiply this second fraction by 2 over 2.
118
And 12 divided by 2 is 6.
119
So I'm going to multiply this fraction.
120
Let's change that color. By 6 over 6.
121
So I'm going to get 3 over 12 plus 2 times 5 is 10.
122
2 times 6 is 12.
123
and then 6 times 1 is 6, 6 times 2 is 12.
124
So now we need to add.
125
3 plus 10 is 13.
126
13 plus 6 is 19.
127
So the final answer is 19 over 12.
128
So that is it for this video.
129
Be sure to check out my next video on subtracting fractions.
130
I'm going to post some links in the description section of this video, so feel free to take a look at that.
131
Thank you.

本节课你将练习什么?

这节课我们通过学习“异分母分数相加”的方法,同时提升英语听力和口语能力。你会跟着视频中的讲解,一边理解数学知识,一边练习英语表达,尤其是如何清晰描述计算步骤。通过影子跟读(shadow speech),你能逐渐跟上视频的语速,提高英语发音的准确性,还能学会用英语讲解数学问题呢!

核心词汇与表达

  • fractions:分数
  • denominators:分母
  • cross multiply:交叉相乘
  • improper fraction:假分数
  • carry over:进位
  • shadow speech:影子跟读

影子跟读练习技巧

视频中的讲解语速适中,语气清晰,非常适合进行英语影子跟读(英语影子跟读)练习。建议你先完整听一遍,熟悉内容后,尝试滞后1-2秒跟读。注意模仿说话人的语调,比如讲解计算步骤时的停顿和重音(如“cross multiply”中的重音在“cross”)。练习时可以把重点放在“如何用英语描述分数加法”上,比如“3 times 4 is 12”“add 8 and 9”这样的表达。坚持用shadow peaks方法练习,不仅能提高英语发音,还能让你更自信地用英语表达数学思维。别担心出错,慢慢来,你会越练越好的!

视频中的语法

说话人最常用的结构,并附上视频中的原话:

结构视频中的用法
最高级 the -est / the most … — 一组中最高或最低的the least common · the lowest
用 “might / may” 表可能 might/may + 动词 — 有可能但不确定的事might find · might even be
“going to” 表将来 be going to + 动词 — 计划或明显即将发生的事we're going to talk · we're going to add · i'm going to post
义务:must / have to / need to 表示某事是必要的need to add · need to write · need to multiply

什么是跟读法?

跟读法 (Shadowing) 是一种有科学依据的语言学习技巧,最初开发用于专业口译员的培训,并由多语言者Alexander Arguelles博士普及。这个方法简单而强大:您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同,跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性,语调,节奏,连读,听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。

影子跟读法: 阅读完整分步指南 →