We deal with concrete numbers in arithmetic
Like two plus two is four or ten minus four is six
Like ten divided by five is two or four times two is eight
These are contained in exact numbers we need to calculate
But in algebraic expressions we see something strange
Letters called variables have values that can change
Look at x plus two, what's the value of x
Well, that depends upon what we call the context
If x equals six, then the value is eight
Or if we say x is three, fives what we'll calculate
The expression's value changes based on the variable's value
And in this case, the sum will be any number plus two
Letters stand for numbers in algebra
They're called variables and they can change on ya
We can evaluate an expression's value
But it depends on the variable's value to make it true
Now let's explore algebraic expressions in our lives
Like shipping a cube-shaped box to my valentine
S to the third power is a value formula, S represents a side
It's the variable letting me know if my gift will fit inside
If the value of S two feet, the volume's eight cubic feet
My gift will fit inside. I hope she thinks it's sweet
Now to wrap my present up, I'll find the surface area
I know A equals 6s squared is the area formula
S is the variable, but since I already know the length's value is two
I'll plug in the two feet and then I know just what to do
Two squared is four, then times six is twenty-four
I'm using algebra to get my crush to like me even more
Letters stand for numbers in algebra
They're called variables and they can change on ya
We can evaluate an expression's value
But it depends on the variable's value to make it true
To identify parts of expressions, we use mathematical terms
Sum, product, factor, quotient, coefficient, term, are words we will learn
We find products when we multiply, quotients when we divide
But let's look at the vocab closer and take a deep dive
For example, let's describe the expression three times two plus four
We can describe it as the product of two factors
And if we look at just two plus four
We can either see it has the sum of two terms, or a single entity
The next word we'll review is the coefficient
Let's look at n plus n plus n plus n
We could say four times n or 4n without the sign
Four is called the coefficient
A number telling us how many times to multiply
Letters stand for numbers in algebra
They're called variables and they can change on ya
We can evaluate an expression's value
But it depends on the variable's value to make it true