# Evaluating Algebraic Expressions with exemples

Each algebraic expression consists of a series of numbers, variables, four operations, parentheses and other mathematical symbols.

Each variable can be replaced by a known number while keeping the same form of the expression. This process is called **evaluating an expression**, i.e. calculating its value by giving each unknown a certain value

In this section we will evaluate algebraic expressions for given values of the variables contained in the expressions. Here are some simple tips to help you be successful.

### Note:

- Replace all occurrences of variables in the expression with open parentheses. Leave room between the parentheses to substitute the given value of the variable.
- Substitute the given values of variables in the open parentheses prepared in the ﬁrst step.
- Evaluate the resulting expression according to the Rules Guiding Order of Operations.

Let's take some examples to make the idea clear.

**Example1:**

Evaluate the expression at .

**Solution:**

Following the tips above, first we replace all occurrences of variable in the expression with open parentheses.

**Example2:**

Evaluate the expression at .

**Solution:**

Following the tips above, first we replace all occurrences of variable in the expression with open parentheses.

**Example3:**

Evaluate the expression at .

**Solution:**

Following the tips above, first we replace all occurrences of variable in the expression with open parentheses.

**Example4:**

Evaluate the expression at .

**Solution:**

Following the tips above, first we replace all occurrences of variable in the expression with open parentheses.

**Example5:**

Evaluate the expression at .

**Solution:**

Following the tips above, first we replace all occurrences of variable in the expression with open parentheses.

**Example6:**

Evaluate the expression at .

**Solution:**

Following the tips above, first we replace all occurrences of variable in the expression with open parentheses.

**Example7:**

Evaluate the expression at and .

**Solution:**

Following the tips above, first we replace all occurrences of variable in the expression with open parentheses.