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Online Quiz (Worksheet A B C D)

Questions Per Quiz = 2 4 6 8 10

Grade 7 - Mathematics
4.11 Finding the value of (a+b) (a-b) (Geometrical Proof)

Find the vlaue of (a+b)(a-b)

Area of rectangle ACDH = AC * AH = (a+b) (a-b)Sq. Units   ..........I
But area of rectangle ACDH = Area of rectangle ACEG - Area of rectangle HDEG

= AC * AG - HD * HG
= (a+b)a - (a+b)b
= a2 + ab - ab -b2
= a2 - b2    ..........II
From I and II
(a+b) (a-b) = a2 - b2
Directions: Solve the following problems. Also write at least ten examples of your own.
Q 1: (3x-2y) (3x+2y) = _____?

Q 2: (6x-7y) (6x+7y) = _____?

Q 3: (9x-7y) (9x+7y) = _____?

Q 4: (7x-6y) (7x+6y) = _____?

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Question 6: This question is available to subscribers only!

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