ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
Adding and Subtracting Rational Expressions 1930 Views
Share It!
Description:
Don’t you hate it when you have too many rational expressions—or too few? Thank goodness for addition and subtraction. We don’t know what we’d do without those two.
Transcript
- 00:03
Adding and Subtracting Rational Expressions a la Shmoop
- 00:07
Scientists finally discovered that the duck-billed platypus is actually the result of an alien [Platypus being sucked into a UFO]
- 00:12
DNA-splicing experiment.
- 00:14
Let's help them to unsplice the duck out of the platypus and see what the heck it originally [Scientists with the platypus on an operating table]
- 00:18
was.
Full Transcript
- 00:19
Of course, we're going to have to simplify things...
- 00:22
We'll be representing the unsplicing with the following equation...
- 00:25
Five x over x plus three minus x minus three over x plus three.
- 00:33
Duck DNA is mathematically represented by x minus three over x plus three. [Duck and a platypus with a DNA helix spinning behind them]
- 00:39
Since they have a common denominator…
- 00:41
…we can just squish them together into five x minus x minus three in parentheses, all [Hands squish the equation together]
- 00:47
over x plus three.
- 00:50
Getting rid of the parentheses, this breaks down into five x minus x plus three all over [Parentheses looks upset]
- 00:56
x plus three.
- 00:57
So the answer is four x plus three over x plus three.
- 01:01
This happens to be the DNA code for that kid from the Sixth Sense. [Kid with a duck on his knee]
- 01:04
We always wondered what happened to him. [Duck lays an egg]
Up Next
It's impressive that these expressions are able to stay so rational even when they're having operations performed on them.
Related Videos
Jack and Jill went up the hill to fetch a pail of water. But what happened when they got up there? They’ve been gone an awfully long time…
Sometimes, we just want fewer y's...or more x's. That's why it's great to know how to add and subtract variables. In real life, though, we try to a...