Evaluating Variable Expressions

Front

What is a variable in mathematics?

Back

A variable is a symbol, often a letter, that represents a number in mathematical expressions or equations.

Front

What does it mean to evaluate a variable expression?

Back

To evaluate a variable expression means to substitute the values of the variables into the expression and perform the necessary operations to find a numerical result.

Front

If x = 3, what is the value of the expression 2x + 5?

Back

The value is 2(3) + 5 = 6 + 5 = 11.

Front

What is the order of operations used when evaluating expressions?

Back

The order of operations is Parentheses, Exponents, Multiplication and Division (from left to right), Addition and Subtraction (from left to right), often abbreviated as PEMDAS.

Front

Evaluate the expression 4a - 3b if a = 2 and b = 1.

Back

4(2) - 3(1) = 8 - 3 = 5.

Front

What is a constant in a mathematical expression?

Back

A constant is a fixed value that does not change, unlike a variable.

Front

How do you simplify the expression 3(x + 4)?

Back

You distribute the 3: 3x + 12.

Front

What is the difference between an expression and an equation?

Back

An expression is a combination of numbers, variables, and operations without an equality sign, while an equation states that two expressions are equal.

Front

If y = 5, what is the value of the expression y^2 - 4y + 1?

Back

5^2 - 4(5) + 1 = 25 - 20 + 1 = 6.

Front

What does it mean to substitute in an expression?

Back

Substituting in an expression means replacing a variable with a specific value.