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Question
Expand (2n – 1)(2n + 3)
Sum
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Solution
(2n – 1)(2n + 3)
Comparing (2n – 1)(2n + 3) with (x + a)(x + b) we have a = –1, b = 3
(x + a)(x + b) = x2 + (a + b)x + ab
(2n + (–1))(2n + 3) = (2n)2 + (–1 + 3)2n + (–1)(3)
= 22n2 + 2(2n) – 3
= 4n2 + 4n – 3
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Chapter 3: Algebra - Exercise 3.3 [Page 91]
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