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### Grade 7 - Mathematics4.40 Formula for a2-b2 Difference of Two Squares

Formula:
Consider the product (a+b).(a-b).
(a+b).(a-b) = a.a + b.a + a.(-b) + b.-b
= a2 + ab - ab - b2
Therefore (a+b)(a-b) = a2-b2
a2-b2 = (a+b)(a-b)

a2-b2 = (a+b)(a-b)

Directions: Solve the following problems. Also write at least ten examples of your own.
 Q 1: (p+q)(p-q) = _____?p2+q22p2-2q2q2-p2p2-q2 Q 2: (9x+5y)(9x-5y) = _____?9x2-5y2(9x)2-(5y)2(9x)2+(5y)2(x)2+(5y)2 Q 3: (c-d)(c+d) = _____?c2+d2c2-d2d2-c22c2-d2 Q 4: (3a-b)(3a+b) = _____?6a2-b29a2-3b23a2-b29a2-b2 Question 5: This question is available to subscribers only! Question 6: This question is available to subscribers only!

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