Algebra 1 > Notes > Lesson_1 - Variables And Expressions

Lesson 1 Variables and Expressions

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Variables • A variable is a letter, or symbol, used to represent a number. • A variable is usually represented by a lower case letter. • In the expression 6x – 3, x is the variable.

Algebraic Expressions • An algebraic expression has one or more variables, one or more numbers and it also has an algebraic operation (addition, subtraction, multiplication, etc)

• X – 2, 3y + 3,

7m 3

Verbal Expressions • Sometimes we need to translate verbal expressions (plain English) into algebraic expressions. • Example: 4 less than 3 times a number. • 3x – 4 , that is 3 times a number minus 4. • Try this one: 3 less than 8 times a number

• And the answer is.. • 8x – 3

• Try another one: • 4 times a number less than 33

• And the answer is.. • 33 – 4x

• Sometimes you will need to be able to look at an algebraic expression and write the verbal translation for it. • 4s + 9h • Which means… The product (multiplication) of 4 and s added to the product of 9 and h.

Power • An expression like xn is called a power. We have two parts to this expression. • The variable x is called the base. • The variable n is called the exponent.

• 31 • 32 • 33

3 to the first power = 3 3 to the second power = 3 X 3 3 to the third power = 3 X 3 X 3

• kn

k to the nth power » That means you multiply k together n times.

• Evaluate. • 44 = 4 ● 4 ● 4 ● 4 = 256 • Try this one • 53

• And the answer is….. • 53 = 5 ● 5 ● 5 = 125