#### Transcript of Algebra Lesson Intro (variables and expressions)

An algebraic expression is a mathematical phrase that can contain constants, variables (like x or y) and operators (like add,subtract,multiply, and divide).

3Y+7

(6-7)/N

9-Y

Variables are used when there is missing information. It is used to write a formula.

Example:

The Vancouver community center sells basketball game tickets at a price of $10. We can use the following formula to find the price of any number of tickets, where n (the variable) represents the number of tickets sold:

Price of tickets = 10 x n

10 x n shows that 10 is multiplied by the number of tickets sold, which is represented by n.

We usually write 10 x n as, (10)(n), 10(n), 10 n, or 10n. (This is done because we avoid x as it may be confused as a variable.)

10n is the expression and the letter n is the variable, whereas 10 is the constant.

Replacing a variable by a number is called substitution.

If you were to buy 10 tickets you would substitute 10 in place of n. What is the cost of 10 basketball tickets? 15?

Expression: 10n

HW TIME

Page 197

Questions 4-24, 29-40,

& 42-45

Algebra is the part of mathematics in which letters and other symbols are used to represent numbers and quantities in expressions and equations.

The symbols used are called variables and constants.

A Variable is a symbol used to represent a number that is unknown. Typically variables are represented with various letters from the alphabet, such as x and y.

A constant is a number or symbol that represents a specific value, such as 5 or pi (3.14).

What are the constants, variables, and operators presented in these examples?

Neither the equal sign or inequality sign are part of an expression.

.

Evaluate the following.

a) n+5, n=5

b)7x-3, x=5

c)y/z, y=15 and z=3

d) 4(n+a), a=5 and n =2

**10 + x = 14**

**2y = 18**

4x + 2z = 14

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