Moving a Binomial From the Denominator

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Moving a binomial from the denominator isn't something you can just do with a pencil and an eraser. Learn about moving a binomial from the denominator with help from a professional math teacher in this free video clip.

Part of the Video Series: Math Measurements
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Video Transcript

Hi my name is Marija. I'm a mathematician and today I'm going to show you how to move a binomial from a denominator. So if I have a rational equation like 10/X plus 4 equals 2 and I've got to get rid of that binomial in the denominator so that I can have a linear equation and solve it, what I'm going to do because the denominator means that I'm dividing by that binomial, is I'm going to multiply this entire side of the equation as well as this entire side of the equation by X plus 4 because whatever I do to one side I've got to do to the other. So when I multiply this entire left side by X plus 4, what's going to happen is they're both just going to cancel out and I'm left with 10. Now on the other side, when I multiply by X plus 4 I've got to be really careful not to just put 2X plus 4 because what's happening is I'm distributing this 2 to that entire binomial and that's the number one misconception. So just remember that if you multiply a number by a binomial, you've got to distribute that number into the binomial, so that really becomes 2X plus 8 and now I've got a two step equation that I can solve. I'm going to do minus 8 on both sides and I'm going to end up with 2 equals 2X and then when I divide by 2 on both sides, I'm going to get X equals 1 and I'm done. My name is Maija and I just showed you how to move the binomial from the denominator.


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