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Find the middle term in the expansion of (2ax-bx2)12.

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Question

Find the middle term in the expansion of `(2ax - b/x^2)^12`.

Sum
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Solution

Since the power of binomial is even, it has one middle term which is the `(12 + 2)^"th"/2` term and it is given by

T7 = `""^12"C"_6  (2ax)^6  ((-b)/x^2)^6`

= `""^12"C"_6  (2^6 a^6 x^6 * (-b)^6)/x^12`

= `""^12"C"_6  (2^6 a^6 b^6)/x^6`

= `(59136a^6b^6)/x^6`

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Chapter 8: Binomial Theorem - Solved Examples [Page 134]

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NCERT Exemplar Mathematics Exemplar [English] Class 11
Chapter 8 Binomial Theorem
Solved Examples | Q 8 | Page 134

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