Binomial Theorem · JEE Preparation Mathematics
Find the two middle terms in the expansion of (2x - 1)^7.
Practice question from Binomial Theorem (JEE Preparation Mathematics), with the correct answer and a step-by-step solution.
medium · Subjective · Q-E393E9
Find the two middle terms in the expansion of (2x - 1)^7.
Answer: Since the expansion has 8 terms, the two middle terms are the fourth and fifth terms. They are T4 = C(7,3)(2x)^4(-1)^3 = -280x^4 and T5 = C(7,4)(2x)^3(-1)^4 = 280x^3. Therefore, the two middle terms are -280x^4 and 280x^3.
Solution
For an expansion with , there are terms, so the middle terms are and . Using gives and .
More from Binomial Theorem
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