WEBVTT
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In the past few minutes we've touched on a
lot of concepts that are going to play a
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really central role in the rest of the
course and really in all math going
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forwards from here. So I would like to do
a review of the algebra vocabulary that
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we've covered so far. I think it's
actually going to amaze you how much we've
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already gone over in a pretty short amount
of time. So first thing first, we have
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numbers, as one might expect in math. So
what are some examples of numbers? Well,
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we could have any number of things. So
like we learned in the very beginning of
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this course, they're all different kinds
of numbers. Some that are pretty simple
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and we use all the time, like 0 or 1 or
46, and some that are a little bit more
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special, like the root of 2 or pi. Then in
contrast to numbers, we also learned about
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variables. So, here we have all different
kinds of symbols, we have some letters, we
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have some sillier things like hearts and
smiley faces, we got some greek letters.
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But regardless of what we write variables
as they all have the same purpose, as we
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learned earlier. Variables are symbols
that we use in equations and expressions
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that serve as slots into which we can plug
other numbers to make our expressions take
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on different values. So comparing numbers
and variables, numbers have fixed values.
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They inherently show certain quantities.
Variables, however, don't show outright
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what they stand for, they're just place
holders into which we can insert different
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numbers. One thing to take note of when
we're looking at what's inside each of
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these circles is that we actually have a
symbol on the number side. That's this pi
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right here. Since pi is an irrational
number, it extends for an infinite number
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of decimal points. Now, it took me an
awfully long time to write all of this
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out. So if I were to write even more, that
would take me even longer. To make our
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lives much more simple, we give this
infinitely long number a special name,
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which is pi. A similar thing happens when
we write square roots. We have a number,
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2, right here but we also have a square
root sign over it. Since the root of 2 is
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also an irrational number the square root
sign is just another way of taking a
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shortcut to not have to write out an
infinite number of decimals. So bottom
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line, when you see symbols, they're almost
always variables. They'll be certain
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cases. Which you'll become well acquainted
with when you see things like pi or like a
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square root sign that are symbols of some
sort but represent numbers.