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Question
In the expansion of (x + a)n if the sum of odd terms is denoted by O and the sum of even term by E. Then prove that 4OE = (x + a)2n – (x – a)2n
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Solution
4OE = (O + E)2 – (O – E)2
= [(x + a)n]2 – [(x – a)n]2
= [x + a]2n – [x – a]2n
Hence, 4OE = (x + a)2n – (x – a)2n
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