Very hard calculus questions

By: Prof. Dr. Fazal Rehman | Last updated: February 15, 2025

Question 1:

\[ \text{Evaluate } \lim_{x \to 0} \frac{\sin(x) – x}{x^3}. \] \[ \text{(a) } -\frac{1}{6}, \quad \text{(b) } 0, \quad \text{(c) } \frac{1}{6}, \quad \text{(d) } \frac{1}{2} \] Answer: A

Question 2:

\[ \text{Evaluate } \int_0^\infty \frac{x^2}{e^x – 1} dx. \] \[ \text{(a) } \frac{\pi^2}{6}, \quad \text{(b) } \frac{\pi^2}{3}, \quad \text{(c) } \frac{\pi^2}{2}, \quad \text{(d) } \frac{\pi^2}{4} \] Answer: B

Question 3:

\[ \text{Find the sum of the series } \sum_{n=1}^{\infty} (-1)^n \frac{\ln n}{n}. \] \[ \text{(a) } -\frac{\pi}{4}, \quad \text{(b) } \frac{\pi}{4}, \quad \text{(c) } 0, \quad \text{(d) } \frac{\pi}{2} \] Answer: A

Question 4:

\[ \text{Evaluate } \int_0^\pi x \ln(\sin x) dx. \] \[ \text{(a) } -\frac{\pi}{2} \ln 2, \quad \text{(b) } -\frac{\pi}{4} \ln 2, \quad \text{(c) } \frac{\pi}{2} \ln 2, \quad \text{(d) } \frac{\pi}{4} \ln 2 \] Answer: A

Question 5:

\[ \text{Evaluate } \sum_{n=1}^{\infty} \frac{(-1)^n}{n^2}. \] \[ \text{(a) } -\frac{\pi^2}{12}, \quad \text{(b) } \frac{\pi^2}{12}, \quad \text{(c) } -\frac{\pi^2}{6}, \quad \text{(d) } \frac{\pi^2}{6} \] Answer: A

Question 6:

\[ \text{Find } \lim_{x \to 0} \frac{\ln(1 + x) – \sin x}{x^3}. \] \[ \text{(a) } -\frac{1}{2}, \quad \text{(b) } \frac{1}{6}, \quad \text{(c) } -\frac{1}{6}, \quad \text{(d) } 0 \] Answer: C

Question 7:

\[ \text{Evaluate } \int_0^1 \frac{\ln(1+x)}{x} dx. \] \[ \text{(a) } \frac{\pi^2}{12}, \quad \text{(b) } \frac{\pi^2}{6}, \quad \text{(c) } -\frac{\pi^2}{12}, \quad \text{(d) } -\frac{\pi^2}{6} \] Answer: A

Question 8:

\[ \text{Find } \lim_{x \to 0} \frac{e^x – e^{-x} – 2x}{x^3}. \] \[ \text{(a) } \frac{1}{3}, \quad \text{(b) } \frac{1}{6}, \quad \text{(c) } -\frac{1}{6}, \quad \text{(d) } \frac{1}{2} \] Answer: B

Question 9:

\[ \text{Evaluate } \sum_{n=1}^{\infty} \frac{1}{n^4}. \] \[ \text{(a) } \frac{\pi^4}{90}, \quad \text{(b) } \frac{\pi^4}{120}, \quad \text{(c) } \frac{\pi^4}{60}, \quad \text{(d) } \frac{\pi^4}{45} \] Answer: A

Question 10:

\[ \text{Evaluate } \int_0^\infty \frac{x^{s-1}}{e^x – 1} dx, \quad \text{where } s > 1. \] \[ \text{(a) } \Gamma(s) \zeta(s), \quad \text{(b) } \frac{\Gamma(s)}{2} \zeta(s), \quad \text{(c) } \Gamma(s) \zeta(s-1), \quad \text{(d) } \frac{\Gamma(s)}{2} \zeta(s-1) \] Answer: A

Question 11:

\[ \text{Find the residue of } f(z) = \frac{e^z}{(z-1)^2} \text{ at } z = 1. \] \[ \text{(a) } e, \quad \text{(b) } 0, \quad \text{(c) } -e, \quad \text{(d) } 2e \] Answer: D

Question 12:

\[ \text{Find } \lim_{n \to \infty} n \left( \int_0^1 x^n e^x dx \right). \] \[ \text{(a) } 1, \quad \text{(b) } e-1, \quad \text{(c) } e, \quad \text{(d) } 0 \] Answer: B

Question 13:

\[ \text{Evaluate } \int_0^\infty e^{-x^2} dx. \] \[ \text{(a) } \frac{\sqrt{\pi}}{2}, \quad \text{(b) } \sqrt{\pi}, \quad \text{(c) } \frac{\pi}{2}, \quad \text{(d) } \frac{\pi}{4} \] Answer: A

Question 14:

\[ \text{Find } \lim_{x \to 0} \frac{x – \sin x}{x^3}. \] \[ \text{(a) } -\frac{1}{6}, \quad \text{(b) } \frac{1}{6}, \quad \text{(c) } 0, \quad \text{(d) } \frac{1}{2} \] Answer: A

Question 15:

\[ \text{Evaluate } \int_0^\infty \frac{x^{3/2}}{e^x + 1} dx. \] \[ \text{(a) } \Gamma(5/2) \zeta(5/2), \quad \text{(b) } \frac{\Gamma(5/2)}{2} \zeta(5/2), \quad \text{(c) } \Gamma(5/2) \zeta(3/2), \quad \text{(d) } \frac{\Gamma(5/2)}{2} \zeta(3/2) \] Answer: B

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