# Recent content by leehuan

1. ### Higher Level Integration Marathon & Questions

Lol my bad. Idk why I decided to switch the cos out for a sin when posting
2. ### Higher Level Integration Marathon & Questions

\int_0^\infty \frac{\sin x}{x^2+1}dx
3. ### Announcement from BOSTES/NESA - 2019 Syllabus Changes for Calculus courses

Does anyone know if the year 11 content is also examinable for the new calculus syllabuses?
4. ### Integration MC Question - North Sydney Boys 2017 Trial

As correctly stated, A and B are good because they both equal to 0, soo they are ruled out. C fails because by taking the odd function f(x) = -x^3, we have \begin{align*} &\quad\int_{-a}^0 f(x)\,dx + \left| \int_0^a f(x)\,dx \right|\\ &= \int_{-a}^0 -x^3\,dx + \left| \int_0^a -x^3\,dx...
5. ### MX2 Integration Marathon 2021

Re: HSC 2018 MX2 Integration Marathon $\noindent Take$f(x)$to be any arbitrary odd function well defined for all$ -\frac\pi2 \leq x \leq \frac\pi2\\ $and let$ I = \int_{-\pi/2}^{\pi/2} \frac{\cos x}{e^{f(x)}+1}\,dx. $\noindent Considering the substitution$u=-x,\\ \begin{align*}I&=...
6. ### MX2 Integration Marathon 2021

Re: HSC 2018 MX2 Integration Marathon \text{Let }I = \int_0^{\pi/6} \ln (\tan x + \sqrt{3} ) \,dx \begin{align*} I &= \int_0^{\pi/6} \ln \left( \frac{ \frac{1} {\sqrt3} - \tan x }{1 + \frac{\tan x}{\sqrt3} } + \sqrt{3} \right)dx\\ &= \int_0^{\pi/6 } \ln \left( \frac{4}{\sqrt3 + \tan x}...
7. ### Announcement from BOSTES/NESA - 2019 Syllabus Changes for Calculus courses

I interpreted that as something like $Find the area between the curves$y=x^2$and$y=1-x^2
8. ### Announcement from BOSTES/NESA - 2019 Syllabus Changes for Calculus courses

Looks like it says "area under curve" which implied just x-axis to me? Unless "under" actually includes "to the left of" as well
9. ### Announcement from BOSTES/NESA - 2019 Syllabus Changes for Calculus courses

This is a bit dumb but are areas w.r.t. the y-axis still in the maths advanced syllabus? I can't find it. (Can find appropriate volumes in ext 1)
10. ### Higher Level Integration Marathon & Questions

\int_0^{10} x^{\lim_{n\to \infty} f^n(x)}\,dx \text{ for }f(x) = \frac12 \left( x + \frac2x\right) \text{where }f^n(x) = \underbrace{f \cdots f}_{n\text{-times}}(x) Shouldn't be hard assuming I didn't mess up typing the question.
11. ### Higher Level Integration Marathon & Questions

@Paradoxica I think I finally figured what it should've been. \int_1^e x \sqrt[6]{x^{-1} \sqrt[20]{x \sqrt[42]{x^{-1} \dots}}}\,dx Well, hopefully.
12. ### MATH2601 Higher Linear Algebra

I'd recommend InteGrand's rearrangement. But it's still fairly easy just using what they give you. \text{Closure condition: Let }x,y\in C_g\text{, so we have} \\ \begin{align*} gx &= xg \\ gy &= yg \end{align*} \noindent\text{Then, with the aid of the associative rule,} \\ \begin{align*} g(xy)...
13. ### MATH2701 Abstract Algebra/Fundamental Analysis

This was in the final exam and I never figured it out. \text{Let }f:\mathbb{R}\to \mathbb{R}\text{ be a convex function. Prove that for any }x,y,z\in \mathbb{R}, \frac{ f(x)+f(y)+f(z) }3 + f \left( \frac{x+y+z}3 \right) \ge \frac{2}{3} \left[ f \left( \frac{x+y}{2} \right) + f \left(...
14. ### MX2 Integration Marathon 2021

Re: HSC 2018 MX2 Integration Marathon Which isn't even 4U. Savage,
15. ### MX2 Integration Marathon 2021

Re: HSC 2018 MX2 Integration Marathon That being said is there a way of doing it using only 4U methods