Algebraic Expressions: Variables, Coefficients, and Constants

 
ALGEBRAIC EXPRESSIONS
 
 
What is the difference between a numeric
expression and an algebraic or variable
expression?
 
 
Numeric Expression
    
Algebraic Expression
  -3  +  2  + 4 – 5
     
     -3x  + 2y – 4z - 5
 
An 
algebraic or variable expression
consists of three parts
 
Variable
Coefficient
Constant
 
The 
variable
 is a symbol or letter that
represents a number.
 
What are the variables in the expression
below?
 
    
- 4x  +  3y  -  8z  +  9
 
The 
coefficient
 is the number that multiplies the
variable. More plainly, it is the number in front of a
variable.
 
What are the coefficients in the expression below?
 
     
- 4x  +  3y  - 8z  +  9
 
The 
constant
 is any term that does not have
a variable.
 
What is the constant in the expression
below?
 
      
- 8  +  5y  + 3x
 
An algebraic expression may be classified as
a monomial.  A 
monomial
  only has one
term.  It is an expression consisting of a
number and a variable or the product of
numbers and variables that have whole
number exponents.  A monomial cannot
have a variable in the denominator.
 
Comprehension Check
 
Identify the expressions that are 
not
monomials.  Justify your answer.
 
-4xy
    
xy/4
   
4 + x
   
0.7x
-1
  
y/x
 
An algebraic expression can also be classified as a
polynomial which is an expression that consists of
more than one term.  Two types of polynomials are
binomials and trinomials
.
 
A binomial has two terms. 
 
Ex:  3x + 4
 
A trinomial has three terms.
 
Ex:  4a
2
  +  3a  + 7
 
EVALUATING ALGEBRAIC
EXPRESSIONS
 
 
Evaluating an algebraic/variable expression 
involves solving it when the
variable/s in that expression are given a numeric value.
 
To 
evaluate
 a variable expression, you first replace each variable with the
numbers to which they are equal.  Then you use the 
order of operations 
to
simplify.
 
Remember!
 
P
lease 
   
E
xcuse 
   
M
y 
  
D
ear 
  
A
unt 
  
S
ally
    
Parentheses
 
Exponents
 
 
 
x
  
    /
  
    
 
+          
  
  -
 
 
(Multiplication and Division are done in the order in which they appear.  Which
ever operation appears first, is done first.  The same applies for addition and
subtraction when both operations are found within a problem.)
 
 
 
EVALUATING EXPRESSIONS EXAMPLES
 
Example 1
 
 
Evaluate   4y – 15  for y = -9
4y - 15
4(-9) – 15
-36 – 15 = 
- 51
 
Example 2
 
 
Evaluate  3ab + c
2  
 for a = 2,
b =-10, and c = 5.
3ab + c
2
3(2)(-10) + 5
2
-60 + 25 =
-45
 
Example 3
 
 
Evaluate    
6(g + h)
 for g=8
and h = 7.
6(8 + 7)
6 (15) = 
90
 
 
LET’S PRACTICE!
 
Evaluate each expression for x = -2, y = 3 and z =-10
 
xyz
   
8y + z
2
   
z/5 + 2
   
4y – x
 
 
2z + xy
   
9 + y
2
   
4xy – z
   
-5(y + z)
2
                                      x
 
EXPANDING ALGEBRAIC
EXPRESSIONS
 
Using the Distributive Property
 
Distributive Property
 
Expanding an algebraic expression involves using the 
distributive property
.  When
the distributive property is used, you multiply the quantity in front(or sometimes in
the back) of the parentheses by each term in the parentheses.  
Remember
 to use
integer rules for multiplication (if multiplying 
same signs – answer is positive, 
if
multiplying 
different signs – answer is negative
).
 
Examples
4(2x – 3) =
 
8x - 12
     
-5(4x – 9)=
 
-20x +45
 
 
0.2 (3b – 15c) = 
.6b – 3c
    
- (5x – 3y + 8z) = 
-5x + 3y – 8z
 
 
(2x + 5)7 = 
14x + 35
     
½ (6e + 8f – 14g) = 
3e + 4f – 7g
 
LET’S PRACTICE!  
EXPAND EACH EXPRESSION
 
-3(x + 5) =
 
2(-8x + 10) =
 
-(4x – 3y + 7z) =
 
-8(-2x – 3 ) =
 
1/3(6x – 45) =
 
SIMPLIFYING ALGEBRAIC
EXPRESSIONS
 
Distributive Property & Combining Like Terms
 
Simplifying expressions involves combining like terms.
Like Terms 
are monomials that have variables raised to
the same powers.
 
What terms are like terms with 4a
2
b?
 
-16ab
   
3ab
2
 
  
-7a
2
b
 
 
11a
2
b
2
  
5a
2
b
 
When combining like terms, you group like terms together.  Then you
use addition rules to combine the coefficients.  Keep the variables.
 
Simplify each polynomial
 
Ex 1
:  
 
- 6x + 5y – 3x + y – 8
    
Ex 2:
 
-2x – 8y + 5x – 4y
 
 
=
 
-6x – 3x + 5y + y – 8
     
=
 
- 2x + 5x - 8y – 4y
 
=
 
- 9x + 6y – 8
 
      
=
 
3x - 12y
 
EX 3:
 
5a – 2b + c – 5b + 4b
    
Ex 4:
 
4x
2
 - 6x + 3x – 4x
2
  + 7x
2
  + 1 - 5
 
=
 
5a – 2b + 4b + c
      
=
 
4x
2
 – 4x
2
 + 7x
2
 – 6x + 3x + 1 – 5
 
=
 
5a + 3b + c
  
      
=
 
7x
2 
 - 3x - 4
 
LET’S PRACTICE!- 
SIMPLIFY EACH EXPRESSION
 
 
-5x + 4x – 7 – x – 2 =
 
3m – 8m – 5d – 2d – 4m =
 
- 8 – b – 5d – 2d – 4m =
 
3y – 2y + 9 – 5y – 4 =
 
- 23g – 12 + 8d – 9g + 3d =
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Explore the difference between numeric and algebraic expressions, learn about the components of algebraic expressions - variables, coefficients, and constants. Discover how to identify variables, coefficients, and constants in expressions. Classify algebraic expressions as monomials, binomials, or trinomials, and differentiate between monomials and non-monomials. Dive into evaluating algebraic expressions.


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  1. ALGEBRAIC EXPRESSIONS

  2. What is the difference between a numeric expression and an algebraic or variable expression? Numeric Expression Algebraic Expression -3 + 2 + 4 5 -3x + 2y 4z - 5

  3. An algebraic or variable expression consists of three parts Variable Coefficient Constant

  4. The variable is a symbol or letter that represents a number. What are the variables in the expression below? - 4x + 3y - 8z + 9

  5. The coefficient is the number that multiplies the variable. More plainly, it is the number in front of a variable. What are the coefficients in the expression below? - 4x + 3y - 8z + 9

  6. The constant is any term that does not have a variable. What is the constant in the expression below? - 8 + 5y + 3x

  7. An algebraic expression may be classified as a monomial. A monomial only has one term. It is an expression consisting of a number and a variable or the product of numbers and variables that have whole number exponents. A monomial cannot have a variable in the denominator.

  8. Comprehension Check Identify the expressions that are not monomials. Justify your answer. -4xy xy/4 4 + x 0.7x-1 y/x

  9. An algebraic expression can also be classified as a polynomial which is an expression that consists of more than one term. Two types of polynomials are binomials and trinomials. A binomial has two terms. Ex: 3x + 4 A trinomial has three terms. Ex: 4a2 + 3a + 7

  10. EVALUATING ALGEBRAIC EXPRESSIONS

  11. Evaluating an algebraic/variable expression involves solving it when the variable/s in that expression are given a numeric value. To evaluate a variable expression, you first replace each variable with the numbers to which they are equal. Then you use the order of operations to simplify. Remember! Please Parentheses Excuse Exponents My x Dear / + Aunt Sally - (Multiplication and Division are done in the order in which they appear. Which ever operation appears first, is done first. The same applies for addition and subtraction when both operations are found within a problem.)

  12. EVALUATING EXPRESSIONS EXAMPLES Example 1 Example 3 Example 2 Evaluate 3ab + c2 for a = 2, b =-10, and c = 5. 3ab + c2 3(2)(-10) + 52 -60 + 25 =-45 Evaluate 4y 15 for y = -9 4y - 15 4(-9) 15 -36 15 = - 51 Evaluate 6(g + h) for g=8 and h = 7. 6(8 + 7) 6 (15) = 90

  13. LETS PRACTICE! Evaluate each expression for x = -2, y = 3 and z =-10 xyz 8y + z2 z/5 + 2 4y x 2z + xy x 9 + y2 4xy z -5(y + z)2

  14. EXPANDING ALGEBRAIC EXPRESSIONS Using the Distributive Property

  15. Distributive Property Expanding an algebraic expression involves using the distributive property. When the distributive property is used, you multiply the quantity in front(or sometimes in the back) of the parentheses by each term in the parentheses. Remember to use integer rules for multiplication (if multiplying same signs answer is positive, if multiplying different signs answer is negative). Examples 4(2x 3) = 8x - 12 -5(4x 9)= -20x +45 0.2 (3b 15c) = .6b 3c - (5x 3y + 8z) = -5x + 3y 8z (2x + 5)7 = 14x + 35 (6e + 8f 14g) = 3e + 4f 7g

  16. LETS PRACTICE! EXPAND EACH EXPRESSION -3(x + 5) = 2(-8x + 10) = -(4x 3y + 7z) = -8(-2x 3 ) = 1/3(6x 45) =

  17. SIMPLIFYING ALGEBRAIC EXPRESSIONS Distributive Property & Combining Like Terms

  18. Simplifying expressions involves combining like terms. Like Terms are monomials that have variables raised to the same powers. What terms are like terms with 4a2b? -16ab 3ab2 -7a2b 11a2b2 5a2b

  19. When combining like terms, you group like terms together. Then you use addition rules to combine the coefficients. Keep the variables. Simplify each polynomial Ex 1: - 6x + 5y 3x + y 8 Ex 2: -2x 8y + 5x 4y = = -6x 3x + 5y + y 8 = - 2x + 5x - 8y 4y - 9x + 6y 8 = 3x - 12y EX 3: 5a 2b + c 5b + 4b Ex 4: 4x2 - 6x + 3x 4x2 + 7x2 + 1 - 5 = 5a 2b + 4b + c = 4x2 4x2 + 7x2 6x + 3x + 1 5 = 5a + 3b + c = 7x2 - 3x - 4

  20. LETS PRACTICE!- SIMPLIFY EACH EXPRESSION -5x + 4x 7 x 2 = 3m 8m 5d 2d 4m = - 8 b 5d 2d 4m = 3y 2y + 9 5y 4 = - 23g 12 + 8d 9g + 3d =

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