Beginning Algebra

What's algebra and algebraic expressions? It's not as hard as it seems, read on to learn more.

In algebra numbers are expressed as letters, with variables and constants. A variable is a number that can change, such as temperatures. That could be expressed as the variable t.

A constant is a number that is as it implies constant. It does not change, and an example could be your date of birth expressed as the constant b.

Let's say that you had an expression x/y . You would learn that x had the value of 4 and y had the value 2. Put in the values of the respective variables and get 4/2 = 2.

Next time the value might change, so that x now had the value of 10, but y still had the value of 2. You would end up with 10/2=5.

If the expression said (2x)/(3y) this simply means to multiply the value of x by 2, and the value of y by 3. Think of it as (2*x)/(3*y).

We'll say that x is 6 and y is 1, and end up with

(2*6)/(3*1) = 12/3 = 4

Now we can look at a + b = c . Here we have three variables, and to solve for c we put in values for a and b. If a is 3 and b is 4 we would get

3 + 4 = 7 thus c would be 7.

We can take this yet another step, and look at a practical example.

The total rainfall for a certain period in two counties is 4 inches. The counties are named x and y. In x the rainfall was 1 inch, how much was the rainfall in y?

You could set this up as

Total = county 1 +county 2 OR Total = x + y

Since we know x and the total we get

4 = 1 + y

Now there's a basic rule that allows you to move additions to the other side of the equality sign, you just have to change the + or - sign in front of the number you want to move. In the equation above 1 or x is a positive number with a hidden + sign in front of it. To move it over on the same side as 4 you must put a negative sign in front of 1. You will end up with

4 -1 = y

Y would thereby equal 3, and the rainfall in county y is 3 inches.