Algebraic Expressions

Method

Evaluating an Expression

Evaluating an expression consists of determining the value of an expression when the variable or variables of the expression take a specific value. This is done by substituting the given value for the variable in question into the expression and then simplifying it. As an example, consider the following expression. (x-1)^2/2 This expression is going to be evaluated considering that x is equal to 5. There are two steps to follow.

1
Substitute the Given Value for x
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In the expression, substitute the given value for every instance of the variable. In this case, substitute 5 for x.

(x-1)^2/2
( 5-1)^2/2

After the substitution, the variable disappeared and the algebraic expression turned into a numeric expression.

2
Simplify the Expression
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Now the expression can be simplified following the order of operations.

(5-1)^2/2
4^2/2
16/2
8

Consequently, when x is equal to 5, the given expression equals 8.

If an expression has more than one variable, each variable is replaced by its given value before all the required operations are performed.

Exercises
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