載入中... 相關課程 Back 帶分數的倒數 (英) 登入觀看 ⇐ Use this menu to view and help create subtitles for this video in many different languages. You'll probably want to hide YouTube's captions if using these subtitles. 帶分數的倒數 (英) : 帶分數的倒數 上傳學習單 下載學習單 相關課程 0 / 750 Find the reciprocal of 2 and 4/5. So if we want to invert this fraction, we have to write it as a pure fraction first, or as an improper fraction. Right now, it's just a mixed number. So let's just write it as an improper fraction. So 2 and 4/5, if we write it as an improper fraction, it's still going to be over 5, but the numerator is now going to be 5 times 2 plus 4, and that's because 2 is 10/5, or 2 times 5 fifths. So let's write it like that. So it's going to be 2 times 5 plus 4. 2 times 5 is 10. 10/5 is the same thing as 2, and then the 4/5 is this 4/5 right there. So this is going to be equal to 2 times 5 is 10 plus 4 is 14: 14/5. So these are equivalent fractions. This is written as a mixed number. This is written as an improper fraction. It's improper because the numerator is bigger than the denominator. Now we want to find the reciprocal. When you find the reciprocal, you just switch the numerator and the denominator. You just flip the fraction. So if you want to take the reciprocal. Let me do this in a new color. If we want to take the reciprocal of this, we just swap the 5 and the 14. So this is going to be: instead of 14/5, it's going to be 5/14. And we're done!