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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: (4x-4y) (4x+4y) = _____?
16x2+16y2
16x2-16y2

Q 2: (17x-15y) (17x+15y) = _____?
289x2-225y2
289x2+225y2

Q 3: (3x-2y) (3x+2y) = _____?
9x2-4y2
9x2+4y2

Q 4: (9x-7y) (9x+7y) = _____?
81x2+49y2
81x2-49y2

Question 5: This question is available to subscribers only!

Question 6: This question is available to subscribers only!


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