1. The term independent of x in the expansion of (x + 1/x)6 is
- A15
- B20
- C6
- D1
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Answer: B. Tr+1 = 6Crx6−rx−r = 6Crx6−2r. For no x, 6 − 2r = 0, so r = 3 and the term is 6C3 = 20.
By Team Megalecture · Updated 4 Nov 2026
28 exam-style questions on Mathematical induction and binomial theorem, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
28 questions · 3 topics · 10 per test
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
Answer: B. Tr+1 = 6Crx6−rx−r = 6Crx6−2r. For no x, 6 − 2r = 0, so r = 3 and the term is 6C3 = 20.
Answer: C. Left: 1 + 4 + 9 = 14. Right: 3 × 4 × 7/6 = 84/6 = 14. 9 is only the last term and 36 is (1 + 2 + 3)2.
Answer: A. n = −2 and the x term is −x: n(n − 1)/2! × (−x)2 = (−2)(−3)/2 × x2 = 3x2.
Answer: D. The basis step checks the first case, P(1). The inductive step then assumes P(k) and proves P(k + 1).
Answer: C. If truth for k always forces truth for k + 1, then P(1) true gives P(2), P(3), ... in turn.
Answer: D. Put x = 1: (1 + 1)n = nC0 + nC1 + ... + nCn = 2n.
Answer: C. (a + x)n has n + 1 terms, from nC0 to nCn. So there are 11 terms.
Answer: A. n3 − n = (n − 1)n(n + 1), a product of three consecutive integers, which always contains a multiple of 2 and of 3. n = 2 gives 6, which rules out 4, 5 and 9.
Answer: D. (1 − x)−1 = 1 + x + x2 + ..., so the (r + 1)th term is xr. The alternating (−1)rxr belongs to (1 + x)−1.
Answer: C. The binomial series for (1 + y)n needs |y| < 1. Here y = −2x, so |2x| < 1, i.e. |x| < 1/2.
28, each with the answer and a short explanation, across 3 topics: Mathematical induction, Binomial theorem for positive integral index, Binomial series. Every chapter test draws ten of them, so you can take it many times.
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
Yes. In practice mode and on your results you can switch the explanations to Urdu.
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