# Algebra 1 Lessons

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Types of symbols that are used in algebra: -

In algebra 1 lessons, we come across two types of symbols, namely
·         Constants
·         Variables.

Definition of constant: - A symbol which has a fixed numerical value in all situations is known as a constant.

For example: - 5, 30, 246, -7, 5 / 3, 7 / 9, 80.5, -9.6, etc.

Whereas a symbol whose value changes with situation is known as a variable, such as; x, y, p, q, 5x, 7z, etc

Note: - In 3 x, 3 is a constant and x is variable but together 3 x is a variable.

Reason: - As the value of x will change so the value of 3x will also change.

Similarly, 3 is a constant and x is variable but together each of 3 + x, x – 3, x ÷ 3, etc. is a variable.

So, we can say that every combination of a constant and a variable is always a variable.

This combination of constant and variable is known as an expression and the value of the expression depend on the value (s)

of its variable (s).

·         3 + x
·         x – 3
·         x ÷ 3

Example 1: Solve for x in the equation 5x – 15 = 20

For a given equation if the value of a variable is unknown, then the equation is solved to find the value of the variable.

Different algebraic operations are used in order to solve the given equation.

5x – 15 = 20

Add 15 on both sides of the equation.

5x -15 +15 = 20 + 15

5x = 35

Now, divide by 5 on both sides of the equation.

5x/5 = 35/5;

x = 7

Hence the value of the unknown variable x is 7

Example 2: If x = 0, the value of the expression x – 3

For a given equation, the value can be calculated by plugging the value of variable in the equation

x-3 = 0 – 3 = - 3