Lesson 8-8 Special Products
Jan 07, 2016
Lesson 8-8
Special Products
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Objectives
• Find the squares of sums and differences
• Find the product of a sum and a difference
Vocabulary
• Difference of squares – two perfect squares separated by a subtraction sign:a2 – b2 = (a + b)(a - b) or (a – b)(a + b).
Multiplying Special Polynomials
Squares of like polynomials in the following forms,where a and b are constants
• Sums: (ax + b)2
– (ax + b)(ax + b) = a2x2 + abx + abx + b2
= a2x2 + 2abx + b2
• Differences: (ax – b)2
– (ax – b)(ax – b) = a2x2 – abx – abx + b2
= a2x2 – 2abx + b2
• One of Each: (ax – b)(ax + b) or (ax + b)(ax – b) – (ax – b)(ax + b) = a2x2 + abx – abx – b2
= a2x2 – b2
Example 1a
Find (7z + 2)2
Square of a Sum
Answer: Simplify.
Check Check your work by using the FOIL method.
F O I L
Example 1b
Square of a Sum
Find (5q + 9r)2
Answer: Simplify.
Example 2
A. Find (3c – 4)2
Square of a Difference
Answer: Simplify.
Square of a Difference
Answer: Simplify.
B. Find (6e – 6f)2
Example 3
Geometry Write an expression that represents the area of a square that has a side length of (2x + 12) units.
The formula for the area of a square is
Area of a square
Simplify.
Answer: The area of the square is square units.
Example 4a
A. Find (9d – 4)(9d + 4)
Product of a Sum and a Difference
Answer: Simplify.
Example 4b
B. Find (10g + 13h3)(10g – 13h3)
Product of a Sum and a Difference
Answer:
Simplify.
Summary & Homework
• Summary:– Square of a Sum (a + b)^2 = a^2 + 2ab + b^2– Square of a Difference (a- b)^2 = a62 – 2ab - b^2– Product of a Sum and a Difference (a-b)(a=b) =
(a+b)(a-b) = a^2 +b^2
• Homework: – pg. 462 14-48 even