تدريب Shadowing: Subtracting Fractions - تعلم التحدث بالإنجليزية عبر الفيديو
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In this lesson, we're going to focus on how to subtract two or three fractions.
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So let's start with this example.
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3 over 5 minus 1 over 2.
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How can we subtract those two fractions?
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The first thing we need to do is multiply the two denominators of the fractions.
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5 times 2 is 10.
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And then we need to cross multiply.
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3 times 2 is 6.
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5 times negative 1 is negative 5.
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So now we need to subtract 6 and 5, which will give us 1.
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So the final answer is 1 over 10.
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So that is the solution to this problem.
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Now let's work on another one.
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So let's subtract 4 over 3 by 3 over 4.
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And let's use the same technique.
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So first, let's multiply the two denominators of the fractions.
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3 times 4 is 12. And then cross multiply.
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4 times 4 is 16.
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3 times negative 3 is negative 9.
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Now, 16 minus 9 is 7.
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So the answer is going to be 7 divided by 12.
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So now it's your turn.
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Go ahead and subtract these two fractions.
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3 over 8 minus 1 over 7 and also 5 over 7 minus 2 over 5.
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So starting with the first example, let's multiply 8 by 7.
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So 8 times 7 is 56.
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and then let's cross multiply.
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3 times 7 is 21 and 8 times negative 1 is negative 8.
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So now we need to subtract.
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21 minus 8 is 13.
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So the answer to the first problem is going to be 13 over 56.
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Now for the next example let's multiply 5, I mean 7 and 5.
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7 times 5 is 35 5 times 5 is 25 and then we have 7 times 2 which is 14
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so now let's subtract 25 and 14 25 minus 14 is 11
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and so this is going to be 11 over 35 by the way I'm going to post some links
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in the description section of this video where you can find more of my videos on fractions, like how to multiply fractions and how to divide them as well and some other stuff too.
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But before we go into subtracting three fractions, let's talk about another method in which we can subtract two fractions.
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So in the previous method we would multiply 9 and 4
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and that will give us 36 and then we would cross multiply.
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5 times 4 is 20 and then 9 times 1 is 9
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but 9 times 1 is negative 9 so it's gonna be 20 minus 9
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which is 11 and so this will give us 11 over 36 now another way in
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which you can do the same problem
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and get the same results is to get the common denominators first before combining the two fractions 9 times 4 is 36.
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So to get a common denominator of 36, we need to multiply the first fraction by 4 over 4, and the second one by 9 over 9.
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4 times 5 is 20, 4 times 9 is 36.
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And so we're going to get this.
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So now that these two are the same, we can combine the numerators of the two fractions.
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So 20 minus 9 is 11.
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And so we're going to get the same answer, 11 over 36.
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Now, this technique is useful if you have multiple fractions.
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Let's say if you want to subtract 3 or 4 fractions, you could do that.
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So let's say if we have 8 over 9 minus 1 over 3 minus 2 over 5.
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So we'll need to find a common denominator of those three fractions So what is the least common multiple of 9, 3, and 5?
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3 already goes into 9 So any multiple of 9 is a multiple of 3
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So we don't really need to worry about this So what is the common multiple between 9 and 5?
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Well, 9 times 5 is 45 So 45 is the lowest number that can go into 9,
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3, and 5 Now 45 divided by 9 is 5 So I'm going to multiply this fraction by 5 over 5
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Now 45 divided by 3 is 15 So I'm going to multiply the second fraction by 15 over 15.
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And 45 divided by 5 is 9.
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So I'm going to multiply the last fraction by 9 over 9.
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5 times 8 is 40.
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5 times 9 is 45.
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15 times 1 is 15, 15 times 3 is 45, 2 times 9 is 18, 5 times 9 is 45.
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And now we need to subtract.
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So 40 minus 15 is 25, and 25 minus 18 is 7.
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So this is going to be 7 over 45. And that's the answer.
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Let's try another example.
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9 over 10 minus 1 over 5 minus 2 over 7.
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Feel free to pause the video and work on that example.
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So let's get a common denominator between 10, 5, and 7.
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So 5 goes into 10, so we don't have to worry about the 5.
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Any multiple of 10 is going to be a multiple of 5.
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So multiples of 10 are 10, 20, 30, 40, all the way to 70.
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Multiples of 7 are 7, 14, 21, 28, all the way to 70.
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If you multiply 10 and 7, you're going to get a common multiple between 10 and 7, which is 70.
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So it turns out that 70 is the common denominator that we want to get to.
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70 divided by 10 is 7.
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So let's multiply the first fraction by 7 over 7.
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70 divided by 5.
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Let's see what that is.
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So let's use long division.
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5 goes into 7 one time.
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5 times 1 is 5.
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And then subtract.
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7 minus 5 is 2.
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Bring that into 0.
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5 goes into 24 times.
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So 70 divided by 5 is 14.
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So we need to multiply this fraction by 14 over 14.
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70 divided by 7 is 10.
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So we're going to multiply the last fraction by 10 over 10.
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7 times 9 is 63.
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And we know 7 times 10 is 70.
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And 5 times 14 is 70.
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And 2 times 10 is 20. So now let's subtract.
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63 minus 14.
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That's 49.
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And 49 minus 20 is 29.
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So the final answer for this problem is 29 divided by 70.
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Let's work on one last example.
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3 over 4 minus 1 over 2 plus 5 over 3 minus 2 over 5.
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Go ahead and try that example.
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So what is a common multiple between 2, 3, 4, and 5?
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Well, we don't have to worry about the 2 because 2 goes into 4.
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So all we need to do is multiply 4 times 3 times 5, which is 60.
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And so 60 is going to be the common denominator that we need to get to.
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60 divided by 4 is 15.
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So we're going to multiply this fraction by 15 over 15.
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60 divided by 2 is 30, so we're going to multiply the second fraction by 30 over 30.
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And 60 divided by 3 is 20, so let's multiply this fraction by 20 over 20.
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And finally, 60 divided by 5 is 12.
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Now let's multiply.
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15 times 3 is 45, and we know 15 times 4 is 60.
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1 times 30 is 30, and 2 times 30 is 60.
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5 times 20 is 100.
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320 is 60.
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2 times 12 is 24, and 5 times 12 is 60.
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So now we'll need to subtract So first let's subtract these two numbers 45 minus 30 is 15
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So we have 15 over 60 And then let's subtract these two 100 minus 24
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100 minus 20 is 80 80 minus 4 is 76 So now we need to add 15 and 76
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15 plus 76 is going to be 91 and so
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that is the final answer it's a 91 over 60
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so that's all i got for this video be sure to
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check out my next video on multiplying fractions thanks for watching
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أنت تتدرب على اللغة الإنجليزية باستخدام "Subtracting Fractions" مع تقنية الـ Shadowing.
ما هي تقنية التظليل الصوتي؟
التظليل الصوتي (Shadowing) تقنية تعلم لغة مدعومة علمياً، طُورت أصلاً لتدريب المترجمين الفوريين المحترفين. الطريقة بسيطة لكنها قوية: تستمع لصوت إنجليزي أصلي وتكرره فوراً بصوت عالٍ — كظل يتبع المتحدث بتأخير 1-2 ثانية. تُظهر الأبحاث تحسناً كبيراً في دقة النطق والتنغيم والإيقاع وربط الأصوات والاستماع والطلاقة.














