Evaluating Expressions and Variables

This video tutorial introduces variables and variable expressions, explaining how variables represent unknown quantities and how to define and evaluate variable expressions. It distinguishes between expressions and equations and provides practical examples of writing expressions for real-life scenarios, such as calculating costs. The video concludes with practice exercises on evaluating expressions using given values.

What is a variable in mathematics?

• A fixed number

• A letter representing an unknown quantity

• A mathematical operation

• A type of equation

If X represents the number of hours you study, what is the range of possible values for X?

• 0 to 24

• 1 to 24

• 0 to 12

• 1 to 12

Which of the following is a variable expression?

• 5

• X + 5 = 10

• 2X = 5

• 2X - 5

What distinguishes an equation from an expression?

• An expression has an equal sign

• An expression has variables

• An equation has an equal sign

• An equation has variables

How would you write a variable expression for the cost of movie tickets if X is the number of adults and Y is the number of children?

• $X + Y

• $9 + $5

• $5X + $9Y

• $9X + $5Y

In the car rental example, what does the variable D represent?

• Number of miles driven

• Total rental cost

• Number of days rented

• Cost per day

What is the result of evaluating 5X + 7 when X equals 6?

• 35

• 42

• 30

• 37

If M equals 9 and N equals 7, what is the value of 4M - 3N?

• 15

• 21

• 36

• 27

What is the value of P squared minus 3Q plus 7 when P is 11 and Q is 8?

• 104

• 97

• 121

• 110

Evaluate 36 divided by D plus 7E minus 9F when D is 9, E is 3, and F is 1.

• 16

• 21

• 25

• 9