## Variables - College Algebra

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Actually, as much as it might surprise
you, we've been doing algebra right here.
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These 2 symbols, the square and the
triangle that we assigned to replace the
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words that we had written earlier are
called variables. In algebra we make a
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distinction between numbers and variables.
Numbers are well, numbers, like 3,000,000
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or 100,000, and variables are generally
represented by symbols or single letters.
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A variable doesn't have a set value like a
number does. Instead, it's value is
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allowed to vary depending on what we
decide that it should equal. We'll talk more
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soon. Numbers will appear either as
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constant terms on their own, just numbers
like 3,000,000 right here, or in terms
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that combine numbers and variables like
this last one on the right. When
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multiplied by a variable or set of
variables, a number is called a
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coefficient. So again, going back to our
variables, I could of chosen any two
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symbols I wanted to represent these two
quantities right here, the square and the
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triangle. I didn't have to choose the
triangle and I didn't have to choose the
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square. In fact picking these two
particular symbols, is actually pretty
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unconventional in math. To give you a
preview of what you're usually going to be
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seeing during this course, I'll write this
equation out with more typical notation.
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We'll most often see the letters X and Y
as your variables in equations in algebra.
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You can also see I've removed the dollar
signs and the commas from the original
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equation down here to make this equation
look a little bit more clean and strictly
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mathematical. You'll notice that I also
sneakily deleted the multiplication sign
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we had in the top equation, and didn't
write it down here at the bottom. When we
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have single terms that involve both
numbers and variables multiplied together,
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we don't usually write the multiplication
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we write the symbols directly next to each
other, with nothing in between,
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multiplication is assumed to be happening
between them. It's like there's an
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invisible multiplication sign written
right here. I'm going to erase that
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though, to remind us that we're not
usually going to see any multiplication
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signs written between numbers and
variables. Although people doing math
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often use the variables y and x in their
equations, I really want you to remember
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that this is not necessary. Triangles and
squares are just as useful as x's and y's.
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No matter what symbol you choose to write
a variable with, the power that it has is
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still the same. It acts as a slot where we
can insert different numbers to make terms
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and expressions take on different values.
So maybe I set this first variable equal
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to 3 and the second equal to -1 or
maybe this is -1/2 and this is 23.
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In certain situations, there will be
restrictions placed on what different
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variables can equal. But, until we have
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leave them written as variables, showing
that their values are still sort of a
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mystery to us.
Cím:
Variables - College Algebra
Video Language:
English
Team:
Udacity
Projekt:
MA008 - College Algebra
Duration:
02:53
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