1. A set A has 128 subsets. The number of elements in A is
- A64
- B7
- C8
- D6
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Answer: B. A set with n elements has 2n subsets, and 27 = 128, so n = 7. Halving 128 to get 64 confuses subsets with elements.
By Team Megalecture · Updated 4 Nov 2026
21 exam-style questions on Maths · Numbers, sets and functions, 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.
21 questions · 2 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. A set with n elements has 2n subsets, and 27 = 128, so n = 7. Halving 128 to get 64 confuses subsets with elements.
Answer: B. (2 − i)2 = 4 − 4i + i2 = 3 − 4i, and the conjugate changes only the sign of the imaginary part: 3 + 4i. The option 3 − 4i is the square itself, not its conjugate.
Answer: B. For an odd function f(−x) = −f(x), so f(−3) = 5, and f(0) = −f(0) forces f(0) = 0. The total is 5 + 0 = 5.
Answer: D. i−35 = i−35 × i36 = i, because i36 = (i4)9 = 1. Finding i35 = −i and ignoring the negative power gives the slip −i.
Answer: B. Complete the square: x2 − 4x + 7 = (x − 2)2 + 3 ≥ 3, with minimum 3 at x = 2. 7 is only the value at x = 0, and 2 is where the minimum occurs, not its value.
Answer: A. If z = x + iy, then z + z̄ = 2x = 6 and z − z̄ = 2iy = 8i, so z = 3 + 4i and |z| = √(9 + 16) = 5. Forgetting the factor 2 gives z = 6 + 8i and |z| = 10.
Answer: C. A = {2, 3, 5, 7} and B′ is the set of even numbers {2, 4, 6, 8, 10}. The only even prime is 2. {3, 5, 7} is A ∩ B and {1, 9} is B − A.
Answer: C. The point (−1, √3) is in the second quadrant with reference angle tan−1√3 = π/3, so the argument is π − π/3 = 2π/3. Writing tan−1(−√3) = −π/3 directly ignores the quadrant.
Answer: A. (f∘g)(1) = f(g(1)) = f(3) = 3(3) − 1 = 8. Working out g(f(1)) = g(2) = 6 uses the wrong order.
Answer: C. Put y = (2x + 1)/(x − 3): xy − 3y = 2x + 1, so x(y − 2) = 3y + 1 and x = (3y + 1)/(y − 2). The reciprocal 1/f(x) is not the inverse function.
21, each with the answer and a short explanation, across 2 topics: Complex numbers, Sets and functions. 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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