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Question
Simplify:
(7a +5b)2 - (7a - 5b)2
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Solution
(7a + 5b)2 - (7a - 5b)2
= (7a)2 + (5b)2 + 2(7a)(5b) - [(7a)2 + (5b)2 - 2(7a)(5b)]
= 49a2 + 25b2 + 70ab - [49a2 + 25b2 - 70ab]
= 70a + 70ab
= 140ab.
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