Variables and Expressions

Variables and Expressions

7.EE.2

Variable

is a letter that represents a number (or quantity) that is either unknown or is changing (variable).

-Example: x,a,.....

Expression

is a combination of variables and normal numbers using operations such as addition, subtraction, multiplication, division, and exponentation.
-Example: 4x+3, 5a-4, 3a, 

 $\frac{27a}{3}$  .......

Multiple Choice

 $3n+7$  Given the expression. What should we do 1st? 

• add 7 first

• multiply n by 3?

Multiple Choice

 $3n+7$  Where  $n=-2$  Show the substitution value. 

•  $3\cdot-2+7$  

•  $3\cdot7+\left(-2\right)$  

Multiple Choice

 $3\left(-2\right)+7=$  

• 13
  

• -1

• 1

• -13

P.E.M.D.A.S

1. Parentheses or grouped together (such as in a numerator or denominator)
2. Exponentiation
3. Multiplication/Division (from left to right)
4. Addition/Subtraction (from left to right)

Evaluate the expression

 $5x+2y-7z$  

x=2, y=10, z=5

 $5\left(2\right)+2\left(10\right)-7\left(5\right)$  

 $10+20-35=$  

 $30-35=$  
 $=-5$  

Which operation did you do first?

Which did you do last?

Terms:A combination of variables and numbers using multiplication or division. They are separated from other terms by addition and subtraction.

Ex: 5x+2y-7z

 $4x^2+7$  State all terms:

Terms  $4x^2,7$  

 $12x+2y-11$  State the terms.

 $12x,\ 2y,\ -11$  
Don't forget the negative sign. 

Multiple Choice

 $x^2-\ y^2$  State the terms:

• 1, 1

•  $x^2,\ -y^2$  

Multiple Choice

State the terms: $\frac{x}{2}+3z-6$  

• 
  

   $\frac{x}{2},\ 3z,\ 6$  
  

•  $\frac{x}{2},\ 3z,\ -6$  

•  $x,\ 2,\ 3z,\ 6$  

Poll

 $3y^2-2xy+x^2$  

State the terms.

•  $3y^2,\ -2xy,\ x^2$  

•  $3y^2,\ -2xy,\ x^2$  

Poll

 $4x^3-2x^2+7x+10$  

State the terms.

•  $4x^3,\ -2x^2,\ 7x,\ 10$  

•  $4x^3,\ 2x^2,\ 7x,\ 10$  

Monomial: An algebraic expression consisting of a single term.

Example. 5x

Multiple Select

Select the monomial

• 
  

  $5x+4$
  

• $5c$

Binomial: an algebraic expression with exactly two terms.

Bi=2

Example 2x+10

Multiple Select

Choose all Binomials

• 5x+4-3

• 4x-3

• 5y

• 5y+4z

Trinomial: An algebraic expression with exactly three terms.

Tri=3

Example 3x+2y-7

Multiple Select

Choose the trinomial:

• 
  

  $\frac{1}{2}x-3$
  

• $4c^2+2c-5$

Complete a-f on your notes and submit them as proof of your learning.

Homework will be posted.