Algebraic expressions can be formed using variables, constants, and mathematical operations. Variables represent letters that can take on any value, while constants represent fixed numbers. There are different types of algebraic expressions including monomials, binomials, and trinomials. The value of an algebraic expression can be found by substituting values for the variables and simplifying. Identities are equations that are always true regardless of the values of variables. Common identities include (a+b)2, (a-b)2, and a2 - b2.

3. Algebraic expressions
Algebraic expressions Constants and Variables
 Algebraic expressions are
formed by using variables
constants and operations of
 Addition
 Subtraction
 Multiplications
 Division
 A collection of letters are
called Variables (eg: x,y,z )
 A collection of real numbers
are called Constants
(eg: 3,5,2)

4. TYPES OF ALGEBRAIC EXPRESSIONS
Polynomial
Monomial
7x
Binomial
3x – 2y
Trinomial
p+q+r

5. Value of algebraic expressions
 If X = 3 and Y= 2 then 2X + 3Y + 5,find the value
sol,
= 2(3)+3(2)+5
= 6+6+5
= 12+5
= 17

6. IDENTITIES
Definition
Special Identities
 An Identities is an equality which is true for all values of
variables in the equality
 Identity 1: (a+b)² =a²+ 2ab + b²
 Identity 2: (a-b)² =a²- 2ab + b²
 Identity 3: a² - b² =(a+b)(a-b)

7. • (x+7)²= ?
• a = x
• b = 7
• = x² + 2(x)(7)+7 ²
• = x² + 14x+49
Identity 1
• (x-7)² =?
• a = x
• b = 7
• = x² - 2(x)(7)+7 ²
• = x²-14x+49
Identity 2
• x² - 6² =?
• a² = x² => a = x
• b² = 6² => b = 6
• = (x + 6)(x- 6)
Identity 3
Examples For Identities

8. EVALUATION
Add the expressions
1. L² - M²,2 L² - M²
Subtract the expressions
1. bc – ca, ca- ab
Write the following in expanded form
1. (2x-3y)²