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### Grade 8 - Mathematics7.25 Special Products - Sum and Difference Pattern: (a+b)(a-b) = a2-b2

#### Formula : (a+b)(a-b) = a2-b2

Example:
Find the product (3x+2y)(3x-2y).
Solution:
Clearly the given expression is in the form of (a+b)(a-b) with 3x for a and 2y for b.
Therefore, (3x+2y)(3x-2y) = (3x)2-(2y)2
= 9x2-4y2

Example:
Find the product (t+5)(t-5).
Solution:
(t)2-(5)2
= t2-25

Directions: Solve the following questions. Also write at least ten examples of your own.
 Q 1: Find the product (9x+2y)(9x-2y).81x2-2y281x2-4y29x2-4y2 Q 2: Find the product (7x+2y)(7x-2y).7x2-4y249x2-2y249x2-4y2 Q 3: Find the product (3x+5y)(3x-5y).9x2-5y23x2-25y29x2-25y2 Q 4: Find the product (5x+9y)(5x-9y).25x2-9y25x2-81y225x2-81y2 Q 5: Find the product (7x+5y)(7x-5y).49x2-25y249x2-5y27x2-25y2 Q 6: Find the product (4x+5y)(4x-5y).4x2-25y216x2-25y216x2-5y2 Q 7: Find the product (5x+2y)(5x-2y).5x2-4y225x2-2y225x2-4y2 Q 8: Find the product (2x+7y)(2x-7y).4x2-7y22x2-49y24x2-49y2 Question 9: This question is available to subscribers only! Question 10: This question is available to subscribers only!

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