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What are Multiplicative Inverses?
What are multiplicative inverses?
Summary
- If the product of two numbers is equal to 1, then those numbers are multiplicative inverses!
- Remember, "product" just means multiplication
- The numbers 5/3 and 3/5 are multiplicative inverses!
- If we didn't know the multiplicative inverse of 5/3, how would we find it?
- We can take the reciprocal of 5/3 to find it's multiplicative inverse
- To find a reciprocal of a fraction, you just have to flip the top and bottom of that fraction!

Notes
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- Remember, "product" just means multiplication
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- For example, 2 and 1/2 are multiplicative inverses because 2•(1/2)=1
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- The reciprocal of a number is just that number as a fraction, but flipped over
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- The numbers 5/3 and 3/5 are multiplicative inverses!
- That means their product is equal to 1
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- (5/3)•(3/5)=1
- The 3's and 5's cancel out, and we're left with 1 as our answer
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- Since the product of 5/3 and 3/5 is equal to 1, they must be multiplicative inverses
- Remember, "product" just means multiplication
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- Since the product of 5/3 and 3/5 is equal to 1, they must be multiplicative inverses
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- How would we figure out any number's multiplicative inverse?
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- Multiplicative inverses have a product that equals 1
- Remember, "product" means multiplication
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- Multiplying a number by it's reciprocal will always be equal to 1
- So a number and it's reciprocal MUST be multiplicative inverses!
- The reciprocal of a fraction is a number that you get from switching the top and bottom of the original fraction
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- If you want to find the reciprocal of a whole number just turn it into a fraction by putting it over 1
- For example, the fraction form of 4 is 4/1
- Then you can just flip the fraction!
- So the reciprocal of 4 (or 4/1) is 1/4
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- You just have to flip the fraction to find a reciprocal
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- To find 3/5, we just found the reciprocal of 5/3
- To find a reciprocal of a fraction, we just have to flip the fraction and make the top the bottom, and the bottom the top
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- Remember, "product" just means multiplication
- Multiplicative inverses have a product equal to 1
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- Multiplicative inverses have a product equal to 1
- Remember, "product" just means multiplication
- (5/3)•(3/5)=1 because the 3's and 5's cancel out leaving just the 1